Category Archives: Science and Technology

ten famous mysteries solved

Explaining the unexplained: 10 famous mysteries solved

Author Rebecca Northfield

Edited By Alex Santiago

The most famous supernatural phenomena can be explained by science. Or can it? Well, yes, it can.

Brown Lady of Raynham Hall

This picture captures one of the most famous ghosts in Great Britain, the Brown Lady of Raynham Hall. Or does it?

It has been said the Brown Lady haunts Raynham Hall in Norfolk, England. She is supposedly the ghost of Lady Dorothy Walpole (1686-1726), sister of Robert Walpole, who is regarded as Britain’s first Prime Minister.

The image was taken by Captain Hubert C Provand, a London-based photographer working for Country Life magazine, and his assistant, Indre Shira. They were taking photographs of Raynham Hall for an article, and had just taken a shot of the Hall’s main staircase.

Allegedly, Shira saw “a vapoury form gradually assuming the appearance of a woman” coming down the stairs, and the duo snapped a picture under his instruction. The later negative showed the ‘Brown Lady’, which was published in Country Life in 1936, along with Shira and Provand’s written account of events.

Critics claimed Shira put a greasy substance on the lens to create the figure, or moved down the stairs during an exposure. There is also a theory of double exposure upon detailed examination, as well as one picture being superimposed over the other due to a patch of reflected light at the top of the right hand banister appearing twice.

The magician John Booth said the ‘Brown Lady’ could be duplicated by natural methods. By covering fellow magician Ron Wilson with a bed sheet – like a last minute Halloween costume – and instructing him to walk down a staircase, the faked image looked very similar to the Lady.

It is also said the ‘Brown Lady’ closely resembles a standard Virgin Mary statue that is found in a Catholic church.

The public were bamboozled by cheap camera trickery. Good effort, though.

Bermuda Triangle

The infamous region of the Atlantic Ocean, which earned its reputation due to claims of planes and ships disappearing between Bermuda, Puerto Rico, and Miami, Florida without a trace, turned out to be not as scary as it seemed.

Bermuda triangle

In 1975, Larry Kusche, a research librarian at Arizona State University, found some disappearance claims were either exaggerated or wholly false. Additionally, the Bermuda Triangle doesn’t actually have an unusual number of shipwrecks or plane crashes when compared to any other areas that experience similar traffic. To explain the mysterious absence of wreckages, the strong current of the Gulf Stream is powerful enough to wash away any evidence of destroyed ships and planes.

Coast Guard records also proved that many disappearances were down to human error, boat failure and other natural sea-based problems. Also, it would be strange for there not to be vanishings due to the colossal size of the triangle.

Stonehenge

Ah, some stacked, Neolithic stones. Wonder what this could be?

Stonehenge is a circle of old stones in Wiltshire, England. Carbon dating makes it between 4,000 to 5,000 years old, so it puzzled many when you look at how advanced the architecture is, given what kind of tech was available back in the day.

Slave labour and even alien activity populated the theories about how the mysterious rocky collection came to be.

We may never know what the structure was used for, but to disprove the notion that its construction was somehow magical, Michigan carpenter Wally Wallington built a Stonehenge replica in his garden, on his own, using only what was available to humans back then. This proved at least the possibility that the celebrated stone circle was pretty much a doddle for even an ancient group of builders if they were tech-​savvy enough.

Sailing stones in Death Valley

At California’s Death Valley there are hundreds of trails from large, rough blocks of rock in the aptly-named Racetrack Playa. It clearly means the stones are moving, but nobody pushes them, and no one has seen them move. Ooooh.

Supernatural theories for the phenomenon include the rocks being remains of a UFO crash, mysterious ‘unseen hands’ that move the rocks, or magnetic fields of some kind.

So what was the best way to figure out how these creepy rocks were moving? Fit them with GPS units, use time-lapse cameras and study the weather, obviously.

Scientists figured out that although Death Valley is blisteringly hot in the summer – its highest recorded temperature stands at 56.7°C – during the mild winter, rain collects to form a shallow lake, which subsequently freezes into thin sheets when the temperatures drop at night.

In the morning, the sun warms the ice, which breaks into small plates. If a plate is under a rock – which can weigh over 300kg – wind and flowing water slowly pushes it. A rock can move 224m in the winter, leaving a trail in the mud.

Flying rods

Is it a bird? Is it a plane? No, it’s probably a moth.

In photographic and video recordings around the world, a strange solar entity – lines of light dashing across the sky – would sometimes occur, with no clear reason why. A common interpretation of these rods was – you guessed it – an incident of the paranormal, or tiny alien life forms. Adorable, right?

Jose Escamilla is a spokesperson for the rod aliens, as he claimed to be the first to film them back in 1994. The location? Roswell, New Mexico, no less. This guy has gone on to lecture on the subject, as well as make more videos of the tiny ‘aliens’. So it must be true?

Alas, this totally plausible theory wasn’t paranormal. It was, well, normal.

Tonghua Zhenguo Pharmaceutical Company in Jilin Province, China, thought Escamilla’s claims were poppycock. With huge nets and surveillance cameras, they captured the spooky rods doing their thing. When they checked the nets, there were no aliens. Just moths and other flying critters.
The rods were actually motion blur – ‘afterimage’ traces of bugs and wingbeats – caught on camera. It’s an optical illusion, and is more likely to occur in interlaced video, where slower recording speed makes moths look like aliens.

Ley lines

A weird connect-the-dots moment occurred in 1921, when archaeologist Alfred Watkins noticed that many ancient sites seemed to line up in a too-straight-to-be-a-coincidence way. He called them ‘leys’, and later, ‘ley lines’.

This sort of finding doesn’t go unnoticed by believers in the supernatural. They think where the leys intersect there are pockets of concentrated energy: deep and mythical power which can be harnessed. There’s one line, from Ireland to Israel, that connects seven locations linked to St Michael.

Sadly though, it all seems to be bogus, and the lines pass through the sites by chance. Watkins himself believed ancient Britons used landscape features as navigation points.

The Nazca Lines of Peru

Discovered in the 1930s (when we could finally fly high enough), the Nazca Lines are massive white geoglyphs – some being 275m across – made from shallow lines dug into the ground. The whole area is about 190 square miles (500km²). They are thought to have religious significance to the Nazca culture.

Given that aeroplanes are thought to have been in short supply between 500 B.C.E. and 500 C.E., how could the Nazca people see what they were doing?

Author Jim Woodman thought it could have been done by using a basic hot air balloon and shouting directions to the diggers below. To test the theory, Woodman made a functioning balloon with materials they would have had back then. The only problem is there is no proof the Nazca people even knew what a balloon was. Popped that theory.

However, wooden stakes at the site, carbon-dated to the Nazca period, have given researchers a hunch that people at the time may have drawn long ropes between stakes to make the lines. So Dr Joe Nickell and three assistants – including an 11-year-old – used the method to make a giant bird. And it only took them a few hours.

Mystery solved.

Ball lightning

Ball lightning is a potentially dangerous atmospheric electrical phenomenon. It’s reported as looking luminous and spherical, and can vary in diameter – from pea-sized to several metres long.

Ball lightning doesn’t happen very often, so it hasn’t been recorded under natural conditions.

It is said to occur during thunderstorms, but it lasts a good deal longer than your usual split-second lightning. Early reports noted that the ball explodes and leaves a sulphurous odour.

I know we’re all about explaining the unexplained here, but the cause of ball lightning remains unclear; scientists can only really theorise about how these little devil balls are created.

The best explanation comes from a team of Brazilian scientists back in 2007. They passed large amounts of electricity through a silicon wafer, which created a vapour. When it cooled, the vapour condensed into an aerosol which glowed when recombined with oxygen, leading to little balls of electricity bouncing around like jumping beans. Because of this, the Brazilian scientists reckon the ball lightning phenomenon occurs when bog-standard lightning strikes quartz-or-silica-rich ground – like sand. The theory has gained such traction that other scientists are rumoured to have agreed. Shocking.

Spontaneous human combustion

Have you ever been so angry that you feel like you’re going to burst into flames? Well, these people look very much as if they did. Spontaneous human combustion was first described in the 1600s: someone would burn to death without an obvious source, the head and trunk being reduced to ash. All that would remain would be the leg or legs, poking out from the remains. Quite horrific.

However, investigation into this frightening phenomenon has shown that exploding fiery humans combusting into dust was actually widely exaggerated.

People are, it turns out, mostly made of water, so the likelihood of us actually randomly bursting into flames is negligible. If you look at images of supposed spontaneous combustion, victims were often near a source of flame, like a fireplace. One further explanation would be the person’s clothing being set on fire by a candle or cigarette. Old age or physical condition justified why the victim couldn’t put out the fire or move away from it. Clothing acts as a sort of wick and when the skin breaks, fat from the body is fuel to prolong the burning. How pleasant.

Corpse candles

The name is a bit gross to begin with. Rather like spontaneous human combustion, but more manufactured.

It’s not how it sounds, though.

Back in the day, when you were transporting your dead loved one to the cemetery across the gloomy marshes, a flame or ball of light would float just above the Earth, seeming to travel with you to and from the burial ground. This was aptly named the corpse candle, following you in your time of deepest grief.

Mystery and folklore surrounded this strange occurrence – many associated the corpse candle with pesky spirits of the dead, or other supernatural wanderers like stillborn and unbaptised babies that were in limbo between heaven and hell. How depressing.

Science has determined that the creepy corpse candles were in fact luminescent barn owls that had fungus growing on them, or, more likely, methane gas made by rotting organic material, which is usually found in swamps and marshes. The gas can produce a low-temperature ‘flame’ through chemiluminescence.

So instead of seeing an attentive spirit, you’d be witnessing the Earth doing a glow-in-the-dark fart. You’re welcome.

SECRET WEAPONS OF THE UNITED STATES

10 Alleged Secret Weapons Of The US Military

Samuel Popejoy Author

Edited By Alex Santiago

The art of war has evolved dramatically with the advent of contemporary technologies. One thing about war, however, hasn’t changed. To win a war, it’s still essential to keep the true strength of your forces and the extent of your arsenal hidden from your opponent. The most important military secrets are only disclosed to the select few who can be trusted to carry out the mission.

For this reason, the US government can’t divulge complete information about its tools and tactics for the national defense to the people it is sworn to serve. So there must be at least some instances when weapons of war have been developed and deployed without the knowledge of the American populace (or the rest of the world).

But what if the opponent of the military-industrial complex, having acquired unwarranted influence, became its own people? What fantastic secrets of kinetic, psychological, biological, and energetic warfare might then be hidden well below the surface of public knowledge?

At least some aspects of the existence and operational parameters of the following 10 weapons have made their way into general awareness. Yet their development begs the question: What other tools of death and destruction might be lurking in the shadows, utterly obscured from the public eye?

10 Directed Energy Weapons

Directed Energy: The Time for Laser Weapon Systems has Come

The Greek mathematician Archimedes may have made history over 2,000 years ago as the first person to ever use a directed energy weapon. According to a mysterious legend, during the Roman invasion of Syracuse, Archimedes rapidly constructed a hexagonal mirror when the Roman admiral Marcellus moved his ships out of the range of bowshot.

Archimedes was apparently able to capture the energy of the Sun and reflect it onto the ships, setting them ablaze and causing them to sink within minutes. MIT students were able to recreate this effect in 2005 but noted that their mirror was only capable of effectively burning a stationary target.

Though scientific knowledge has advanced a great deal since the days of Archimedes, the underlying theoretical principles of directed energy weapon (DEW) technology remain the same. A DEW inflicts damage from a distance by firing an intensely concentrated beam of energy toward a target.

Different types of DEWs fire different types of energy, but the most popularized form of directed energy weapon in use today is the high energy laser (HEL). These DEWs are just like the lasers seen in science fiction movies. They fire a soundless beam of energy, invisible at certain frequencies, that can incinerate a target from hundreds of miles away.

HELs have been developed by contractors like Lockheed Martin for use in missile defense and space war, but some believe that these weapons might have been designed with much more sinister purposes in mind.

During the Thomas Fire that ravaged California in December 2017, many witnesses and researchers noted property damage that seemingly defied every preconceived notion of how a wildfire should behave. Though wildfires use foliage to spread, entire blocks of houses burned to the ground while the surrounding trees remained untouched.

Though no official explanation of this anomalous phenomenon is forthcoming, multiple witnesses across California recorded video of beams of light coming down from the sky as the blaze spread across the state. Given the fact that HELs are commonly mounted on the nose cones of planes, some have concluded that the mayhem wreaked by the Thomas Fire was boosted with directed energy weaponry.

9 Long Range Acoustic Devices

USA: Sound cannon blasts curfew defiant protesters in Ferguson

A new type of crowd control weapon came to the fore during the Ferguson, Missouri, protests of 2014. As an active demonstration of the newfound capabilities of an increasingly militarized American police state, countermeasures employed by the Ferguson Police Department to quell civil unrest included the use of LRAD sound cannons.

Capable of projecting voice commands over a distance of 5.5 miles (9 kilometers), a Long Range Acoustic Device (LRAD) inflicts grievous bodily pain upon anyone within 330 feet (100 meters) of its sound path. LRAD manufacturers are careful to call their products “devices” rather than “weapons” for public relations reasons, but anyone who has endured the effects of an LRAD is well aware of the difference between the truth and the spin.

Just ask the US diplomats stationed in Cuba who recently started losing their hearing. Soon after the detente between the United States and Cuba that transpired in 2015, diplomats deployed to the newly reopened US embassy on this Caribbean island nation started reporting a sudden and permanent loss of hearing.

US investigators concluded that the diplomats had been hit with an advanced and unnamed acoustic device that doesn’t make any audible sound but causes irreparable damage to the ears and brain of anyone in its path. This incident was considered so serious that the United States expelled two Cuban diplomats from their embassy in Washington.

However, the exact nature of this LRAD-like device and the identity of the agents responsible for its use on American officials are still unknown. If a sonic weapon was indeed used on US diplomats in Cuba, this would be an unprecedented incident in the history of international relations.

8 Low-Frequency Microwave Mind Control

Microwaves suspected in attacks on US diplomats in Cuba and China

The apparent sonic attacks on the US embassy in Cuba rekindled decades-old fears about a different kind of secret weapon. In 1965, at the height of the Cold War, the Pentagon discovered that the Soviets were blasting the US embassy in Moscow with extremely low-frequency (ELF) microwave radiation.

While far too weak to cook anything, it was determined that the so-called Soviet Signal carried the possibility of affecting the health or altering the behavior of the embassy staff. Instead of doing anything to stop it, the Pentagon decided to study the potential effects of the signal and attempt to mimic them back home.

DARPA, then a freshly-minted branch of the Department of Defense, subsequently founded an initiative called Project Pandora and began researching the effects of ELF microwave radiation on primate subjects. Though the results were inconclusive, project leader Richard Cesaro remained convinced until Pandora’s disbanding in 1969 that ELF radiation posed a serious threat to the national security of the United States.

The Pentagon never figured out what the Soviets were up to at the American embassy and opted to solve the situation by wrapping the embassy in a building’s equivalent of a tinfoil hat: An aluminum screen was erected to surround the perimeter of the complex.

Though DARPA may have closed the case on ELF radiation in 1969, studies have since indicated that low-frequency microwave and radio waves may indeed have a deleterious effect on the human body. It’s even been demonstrated that the signals emitted and received from cell phones have an effect on the functioning of the mind that frequently shows itself in the disruption of natural sleep cycles.

Today’s world is absolutely saturated by invisible signals that keep us connected and informed. But how much do we truly know about this all-pervasive radiation and how it might be affecting our health and even our thoughts?

7 Heart Attack Guns

SYND 7 9 75 CIA DIRECTOR WILLIAM COLBY BEFORE SENATE COMMITTEE

In the wake of the Watergate scandal of the early 1970s, Democratic Senator Frank Church led a committee dedicated to getting to the bottom of any actions perpetrated by the CIA that may have violated the charter of this secretive intelligence agency. It was believed that the CIA had accrued undue unilateral power under the pretext of the Cold War, and the Church Committee was assembled to expose this nefarious plot to the American people.

Though history shows us that the attempts of the Church Committee to curb the totalitarian zeal of the CIA were all but ineffective in the long run, a few interesting findings were uncovered during the course of this 1975 investigation. One such discovery was the so-called “Heart Attack Gun,” a modified pistol that was capable of delivering a nearly undetectable but absolutely lethal dose of shellfish toxin into the body of a distant target.

The darts fired by this soundless gun would theoretically leave a pinprick no larger than a mosquito bite and dissolve almost instantly into the tissues of the body after delivering a payload so poisonous that the target would be almost guaranteed to have a heart attack within moments. It’s unknown whether or not the “Heart Attack Gun” was ever used, but for all we know, it could still actively be in use today.

6 Magneto Hydrodynamic Explosive Munitions

Explosively Formed Penetrators | Combat Tech

In Arthur C. Clarke’s book Earthlight, the legendary science fiction author of the 20th century conceives of a futuristic weapon that uses electromagnetism to propel a jet of molten metal miles into space, spearing and destroying an attacking battleship. This type of armor-piercing weapon isn’t entirely unheard of. Since World War II, various arms manufacturers have supplied combatants with tools of war called self-forging penetrators (SFPs).

Making use of a chemical explosion and a metal liner, SFPs propel themselves at an armored vehicle and then change their shape to penetrate the target. However, conventional SFPs are inefficient and hard to use, giving rise to the demand for a more effective armor penetration weapon.

DARPA has developed a specialized projectile to fit this niche called the Magneto Hydrodynamic Explosive Munition (MAHEM). Using electromagnetism to form and direct a sustained jet of molten metal at an armored target, MAHEM is much more adaptable than a conventional SFP and closely resembles the fictional weapon featured in Earthlight.

Beyond these basic details, not much is known about this secretive military project. However, China’s Nanjing University of Science and Technology has apparently reverse engineered MAHEM for its own purposes.

As with many other aspects of the shadowy war for global supremacy currently being waged between the superpowers of the East and West, the full details surrounding the development and deployment of this fearsome weapon may never fully filter their way into the public awareness.

5 Biological Weaponry

Between 1949 and 1969, the United States military tested biological weapons on its own people without their knowledge or consent. One such experiment occurred in 1950 when a US Navy ship sprayed billions of tiny microbes into the atmosphere over San Francisco, causing a massive upsurge in illness and potentially killing one resident.

Another took place in the subway system under New York City in 1966 when researchers dropped light bulbs filled with bacteria onto the tracks to test how far the motion of a train would carry these potentially deadly pathogens. Still other experiments consisted of engulfing entire cities in a cloud of zinc cadmium sulfide under the pretext of providing a smoke screen to hide the population in the event of the outbreak of nuclear war.

The military tells us that all this was done to learn how to better protect us from foreign adversaries, but many wonder whether the benefits of such reckless experimentation truly outweigh the costs.

However, dangerous pathogens released into the atmosphere might be the least of the biological threats to which the American people have been exposed by their government. In 2016, DNI director James Clapper expressed his concerns that gene editing technology might become a weapon of mass destruction if it fell into the wrong hands.

The science of gene editing has proliferated throughout the modern world, seemingly with little to no thought given to the potentially disastrous ramifications of tinkering around with the genetic structure of the biosphere.

While naturally occurring pathogens are bad enough, genetic engineering has given rise to the potential existence of secretly developed biological weapons that could wipe out entire national populations practically overnight. But microbes given superpowers by mad scientists might actually pose less of a danger than other types of genetically modified organisms (GMOs) that have been let loose among an unwitting populace.

In 2013, a group of around 300 scientists formally rejected the premise that there is a scientific consensus on the safety of GMOs for human consumption. This statement led numerous restaurant and grocery chains such as Chipotle and Trader Joe’s to outright ban GMOs from their kitchens and shelves.

Yet agribusiness corporations continue to alter the genetic code of vital crops like corn and soybeans under the protection of an army of scientific publications and news outlets that repeatedly assure their audiences that GMOs pose no threat to the human body or to the biosphere.

Agribusiness giants like Monsanto are heavily subsidized by the United States government. If GMOs truly are detrimental to human health, the unending spread of these unnatural organisms could be serving as a covert continuation of the government’s deadly habit of exposing its people to biological weapons.

4 Subliminal Messaging

It’s been well established that subliminal messaging is used extensively in advertising. This type of marketing usually exploits the baser urges of the populace to influence them to buy a product or service. But what if the same principles used in subliminal advertising are also being used by the United States intelligence community for the purposes of espionage or even mind control?

A formerly secret CIA document titled “The Operational Potential of Subliminal Perception” describes in precise detail the prescribed methodology for gaming the principles of subliminal perception to persuade someone to do something that they usually wouldn’t do.

While the author of the document ultimately concludes that the operational effectiveness of subliminal perception is “extremely limited,” the CIA is widely known for its knack for operating within the strictures of extreme limits and still accomplishing its clandestine objectives with flying colors.

3 Flying Aircraft Carriers

Gremlins: Airborne Launch & Recovery of Unmanned Aerial Systems

In the late 1920s, the United States Navy began exploring the tactical potential of airborne aircraft carriers. Two zeppelin-style airships were constructed, the USS Akron and the USS Macon, both of which carried a crew of 60 men and were capable of deploying and recovering Sparrow hawk fighter planes in flight. However, both Navy flying aircraft carriers met unfortunate ends and their remains now rest at the bottom of the ocean.

Recently, however, rumors have surfaced of DARPA’s plans to reopen this chapter of American history and initiate another attempt to develop airborne aircraft carriers for military use. This time, these proposed sentinels of the skies would carry drones instead of manned warplanes. Called the “Gremlins” program, this audacious DARPA initiative would consist of modified C-130 air transports loaded with stealthy drones capable of penetrating enemy defenses undetected.

Given DARPA’s reputation for suddenly announcing the planning stages of already-completed projects as soon as their cover might be blown, it’s reasonable to wonder whether there might already be “Gremlins” flying over our heads. If the fanciful testimony of supposed secret space program insiders like Corey Goode is to be believed, there may even be Avengers-style Air Force “Helicarriers” patrolling the skies now, rendered undetectable by advanced cloaking technology.

2 Project Thor

‘Rods from God’ Weapon System Gets Another Look

Potentially overshadowing the MOAB as the most lethal non-nuclear weapon in the United States’ arsenal, Project Thor is a technology designed by Jerry Pournelle in the 1950s that would obliterate enemies with bolts from above.

Colloquially termed “rods from God,” this type of Kinetic Energy Penetrator (KEP) would theoretically consist of a pair of satellites. One serves as a targeting hub, and the other is equipped with 6-meter-long (20 ft) tungsten rods that would be dropped on a target from orbit. Capable of penetrating hundreds of feet into the Earth’s crust, these thunderbolts from Thor would produce damage equivalent to a nuclear blast without the fallout.

Though the cost of delivering such rods into orbit is seen as prohibitive, reopening the Project Thor initiative was seriously considered as recently as the George W. Bush administration. With $21 trillion supposedly appropriated without authorization by the Department of Defense and a few other agencies, it’s hard to know what potentially cost-prohibitive theoretical projects the United States government might be silently making into reality without the knowledge or consent of its people.

1 HAARP

Behind the gates of HAARP Alaska ~ Are the conspiracies real?

Hugo Chavez brought international attention to the HAARP facility in Alaska when he accused the United States Air Force of using this high-frequency transmitter array to trigger the 2010 Haiti earthquake. Until this point, casting aspersions on this United States Air Force research station was a faux pas committed by only the looniest of tinfoil hatters.

Theories about the darker side of HAARP were supposedly put to rest when the Air Force announced that this ionospheric research complex would be closing its doors in 2014. But the speculation was kindled back into flame when HAARP was reopened in 2017 by the University of Alaska Fairbanks (UAF).

Admittedly, it probably wasn’t a good choice from a PR perspective on the part of UAF to pick the artificially induced manifestation of a weather phenomenon as their first experiment. When HAARP’s new custodians announced their plans to create a version of the aurora borealis that was invisible to the naked eye in the skies over Alaska, many took this as confirmation of this controversial research station’s weather-manipulating abilities.

Although the HAARP program has been repeatedly accused of manipulating the weather and broadcasting mind control signals, none of these claims have been clearly demonstrated to be either true or false so far.

Samuel is a freelance writer and inquirer into the unknown. By rejecting the authority of conventional belief systems while grounding his perspectives in the core of human experience, he manifests content that dissolves barriers between perception and comprehension. Follow Samuel on Twitter.

LIVING CREATURES IN OUR SKIN

Meet The Mites That Live On Your Face

May 21, 20199:20 AM ET

CREATOR JOSH CASSIDY

Edited By Alex Santiago

It might give you the creepy-crawlies, but you almost certainly have tiny mites living in the pores of your face right now.

They’re known as Demodex or eyelash mites, and just about every adult human alive has a population living on them.

The mostly transparent critters are too small to see with the naked eye. At about 0.3 millimeters long, it would would take about five adult face mites laid end to end to stretch across the head of a pin.

“They look like kind of like stubby little worms,” says Michelle Trautwein, an entomologist at the California Academy of Sciences in San Francisco.

Demodex face mites got their name from the Greek words for “fat” and “boring worm,” but they’re not really worms at all. They’re actually arachnids — related to ticks and, more distantly, to spiders.

Michelle Trautwein, an entomologist at the California Academy of Sciences in San Francisco, tested more than 2,000 people and found DNA evidence of face mites on every single one of them.

Trautwein studies our relationship with these microscopic stowaways by looking at their DNA. Her findings suggest that people in different parts of the world have different face mites. “They tell a story of your own ancestry and also a story of more ancient human history and migration,” she says.

But before she could tell that story, she needed to find the mites.

“We use a little spoon and scrape it across the kind of greasier parts of someone’s face, which isn’t as bad as it sounds,” Trautwein says.

Once the samples have been collected, she takes them to the lab to look at the genetics.

Trautwein has tested more than 2,000 people, including tourists from all around the world that make their way to the California Academy of Sciences. And she’s found DNA evidence of face mites on every single one of them.

“No one is thrilled at the initial notion that they have arachnids on their face,” Trautwein says. “But people are often curious — even in their revulsion.”

But how could these creatures live on so many people and still go unnoticed?

Our skin is mostly covered by a thin layer of peach-fuzz called vellus hair, with a few notable exceptions such as the palms of our hands and feet. The shaft of each one of those tiny hairs grows out of its own follicle.

Face mites — Demodex folliculorum and Demodex brevis — spend their days facedown inside your hair follicles, nestled up against the hair shaft, where you can’t see them.

face mite

They eat sebum, the greasy oil your skin makes to protect itself and keep it from drying out. The sebum is produced in sebaceous glands, which empty into the hair follicles and coat both the hair shaft and face mite.

That’s why the greasiest parts of your body, such as around the eyes, nose and mouth, likely harbor a higher concentration of mites than other areas.

The mites live for about two weeks. They spend most of their time tucked inside the pores, but while people sleep, they crawl out onto the skin’s surface to mate and then head back to lay their eggs.

Since they live inside your pores, you can’t scrub them off by washing. It’s basically impossible to get rid of all of your face mites.

So how does Trautwein find and study a particular mite? With glue.

“I actually put glue on a glass microscope slide and stick it onto a person’s forehead,” she says. “Then I slowly peel it off. I look under a microscope for mites that are stuck in the follicles that stick up from the thin layer of skin that got peeled off.”

“It can be pretty addictive and exciting,” she adds. “It’s sort of a meditative process of looking through this microforest of follicles and hairs and looking for just the right potential movement or shape.”

It seems our immune system is able to keep their numbers in check, but some people can experience problems with the mites.

“When you tell patients that they have face mites, first of all, they freak out,” says Kanade Shinkai, a dermatologist at the University of California, San Francisco.

Since face mites live inside your pores, you can’t wash them off. But for a majority of people, they’re harmless.

Shinkai occasionally treats patients who have an overload of face mites, which results in a condition called demodicosis.

“There is a very particular look to people suffering from demodicosis. We call it the Demodex frost,” she says. “It’s sort of a white sheen on the skin. And if you look really closely, you can see [it] coming out of every pore. If you scrape those pores, you can see it frothing with little Demodex face mites.”

The condition is relatively rare and is often connected to a decline in the immune system, such as receiving immunosuppressive drugs after transplant surgery, chemotherapy orimmunodeficiency diseases such as AIDS.

Demodicosis can also be triggered by local suppression of the immune system, like using itch-relieving hydrocortisone cream on the face.

It usually comes on fast. “Patients almost universally describe this explosive development of like pustules like whiteheads on their face. It’s really dramatic,” Shinkai says. “And what’s really dramatic about it is that they’re often fine the day before, and then they develop it overnight.”

For the vast majority of people, though, face mites are nothing to worry about. While some studies have found loose connections between Demodex and diseases like rosacea, the evidence hasn’t shown a strong link.

“What’s really confusing is that if you go into your office and scrape everyone’s face, you would find Demodex probably on everybody,” Shinkai says. “And people who have low burden of Demodex may have no or very severe disease and vice versa.”

Trautwein also sees face mites more as a source of interest than of fear.

“They’re not dangerous in a broad sense because we all have them and most of us seem to be cohabiting quite well with them,” Trautwein says. “We mostly share them within family units, and it seems like you are probably initially colonized soon after birth, most likely by your mother, traditionally speaking in human history.”

Looking at your mites, researchers such as Trautwein can usually tell something about your geographical ancestry — what part of the world your ancestors came from.

“Face mites are definitely the species of animal that we have the closest connection with as humans, even though most of us don’t know about them or ever see one in our lifetime,” she says. “We still have this very ancient and intimate relationship, and it seems clear that we’ve had these face mite species with us for all of our history. So they are as old as our species, as old as Homo sapiens.”

SECRET KILL LIST OF USA GOBERTMENT DURING OBAMA PRESIDENCY

President Obama in the Oval Office with Thomas E. Donilon, left, the national security adviser, and John O. Brennan, his top counterterrorism adviser.
President Obama in the Oval Office with Thomas E. Donilon, left, the national security adviser, and John O. Brennan, his top counterterrorism adviser.Credit…Pete Souza/The White House

By Jo Becker and Scott Shane

Edited By Alex Santiago

WASHINGTON — This was the enemy, served up in the latest chart from the intelligence agencies: 15 Qaeda suspects in Yemen with Western ties. The mug shots and brief biographies resembled a high school yearbook layout. Several were Americans. Two were teenagers, including a girl who looked even younger than her 17 years.

President Obama, overseeing the regular Tuesday counterterrorism meeting of two dozen security officials in the White House Situation Room, took a moment to study the faces. It was Jan. 19, 2010, the end of a first year in office punctuated by terrorist plots and culminating in a brush with catastrophe over Detroit on Christmas Day, a reminder that a successful attack could derail his presidency. Yet he faced adversaries without uniforms, often indistinguishable from the civilians around them.

“How old are these people?” he asked, according to two officials present. “If they are starting to use children,” he said of Al Qaeda, “we are moving into a whole different phase.”

It was not a theoretical question: Mr. Obama has placed himself at the helm of a top secret “nominations” process to designate terrorists for kill or capture, of which the capture part has become largely theoretical. He had vowed to align the fight against Al Qaeda with American values; the chart, introducing people whose deaths he might soon be asked to order, underscored just what a moral and legal conundrum this could be.

Mr. Obama is the liberal law professor who campaigned against the Iraq war and torture, and then insisted on approving every new name on an expanding “kill list,” poring over terrorist suspects’ biographies on what one official calls the macabre “baseball cards” of an unconventional war. When a rare opportunity for a drone strike at a top terrorist arises — but his family is with him — it is the president who has reserved to himself the final moral calculation.

“He is determined that he will make these decisions about how far and wide these operations will go,” said Thomas E. Donilon, his national security adviser. “His view is that he’s responsible for the position of the United States in the world.” He added, “He’s determined to keep the tether pretty short.”

Nothing else in Mr. Obama’s first term has baffled liberal supporters and confounded conservative critics alike as his aggressive counterterrorism record. His actions have often remained inscrutable, obscured by awkward secrecy rules, polarized political commentary and the president’s own deep reserve.

In interviews with The New York Times, three dozen of his current and former advisers described Mr. Obama’s evolution since taking on the role, without precedent in presidential history, of personally overseeing the shadow war with Al Qaeda.

They describe a paradoxical leader who shunned the legislative deal-making required to close the detention facility at Guantánamo Bay in Cuba, but approves lethal action without hand-wringing. While he was adamant about narrowing the fight and improving relations with the Muslim world, he has followed the metastasizing enemy into new and dangerous lands. When he applies his lawyering skills to counterterrorism, it is usually to enable, not constrain, his ferocious campaign against Al Qaeda — even when it comes to killing an American cleric in Yemen, a decision that Mr. Obama told colleagues was “an easy one.”

His first term has seen private warnings from top officials about a “Whac-A-Mole” approach to counterterrorism; the invention of a new category of aerial attack following complaints of careless targeting; and presidential acquiescence in a formula for counting civilian deaths that some officials think is skewed to produce low numbers.

The administration’s failure to forge a clear detention policy has created the impression among some members of Congress of a take-no-prisoners policy. And Mr. Obama’s ambassador to Pakistan, Cameron P. Munter, has complained to colleagues that the C.I.A.’s strikes drive American policy there, saying “he didn’t realize his main job was to kill people,” a colleague said.

A picture of President George W. Bush is replaced with one of President Obama at Guantánamo Bay, Cuba.
A picture of President George W. Bush is replaced with one of President Obama at Guantánamo Bay, Cuba.Credit…Pool photo by Brennan Linsley

Beside the president at every step is his counterterrorism adviser, John O. Brennan, who is variously compared by colleagues to a dogged police detective, tracking terrorists from his cavelike office in the White House basement, or a priest whose blessing has become indispensable to Mr. Obama, echoing the president’s attempt to apply the “just war” theories of Christian philosophers to a brutal modern conflict.

But the strikes that have eviscerated Al Qaeda — just since April, there have been 14 in Yemen, and 6 in Pakistan — have also tested both men’s commitment to the principles they have repeatedly said are necessary to defeat the enemy in the long term. Drones have replaced Guantánamo as the recruiting tool of choice for militants; in his 2010 guilty plea, Faisal Shahzad, who had tried to set off a car bomb in Times Square, justified targeting civilians by telling the judge, “When the drones hit, they don’t see children.”

Dennis C. Blair, director of national intelligence until he was fired in May 2010, said that discussions inside the White House of long-term strategy against Al Qaeda were sidelined by the intense focus on strikes. “The steady refrain in the White House was, ‘This is the only game in town’ — reminded me of body counts in Vietnam,” said Mr. Blair, a retired admiral who began his Navy service during that war.

Mr. Blair’s criticism, dismissed by White House officials as personal pique, nonetheless resonates inside the government.

William M. Daley, Mr. Obama’s chief of staff in 2011, said the president and his advisers understood that they could not keep adding new names to a kill list, from ever lower on the Qaeda totem pole. What remains unanswered is how much killing will be enough.

“One guy gets knocked off, and the guy’s driver, who’s No. 21, becomes 20?” Mr. Daley said, describing the internal discussion. “At what point are you just filling the bucket with numbers?”

‘Maintain My Options’

A phalanx of retired generals and admirals stood behind Mr. Obama on the second day of his presidency, providing martial cover as he signed several executive orders to make good on campaign pledges. Brutal interrogation techniques were banned, he declared. And the prison at Guantánamo Bay would be closed.

What the new president did not say was that the orders contained a few subtle loopholes. They reflected a still unfamiliar Barack Obama, a realist who, unlike some of his fervent supporters, was never carried away by his own rhetoric. Instead, he was already putting his lawyerly mind to carving out the maximum amount of maneuvering room to fight terrorism as he saw fit.

It was a pattern that would be seen repeatedly, from his response to Republican complaints that he wanted to read terrorists their rights, to his acceptance of the C.I.A.’s method for counting civilian casualties in drone strikes.

The day before the executive orders were issued, the C.I.A.’s top lawyer, John A. Rizzo, had called the White House in a panic. The order prohibited the agency from operating detention facilities, closing once and for all the secret overseas “black sites” where interrogators had brutalized terrorist suspects.

“The way this is written, you are going to take us out of the rendition business,” Mr. Rizzo told Gregory B. Craig, Mr. Obama’s White House counsel, referring to the much-criticized practice of grabbing a terrorist suspect abroad and delivering him to another country for interrogation or trial. The problem, Mr. Rizzo explained, was that the C.I.A. sometimes held such suspects for a day or two while awaiting a flight. The order appeared to outlaw that.

Mr. Craig assured him that the new president had no intention of ending rendition — only its abuse, which could lead to American complicity in torture abroad. So a new definition of “detention facility” was inserted, excluding places used to hold people “on a short-term, transitory basis.” Problem solved — and no messy public explanation damped Mr. Obama’s celebration.

A house destroyed by authorities in Dera Ismail Khan, Pakistan.
A house destroyed by authorities in Dera Ismail Khan, Pakistan.Credit…Ishtiaq Mehsud/Associated Press

“Pragmatism over ideology,” his campaign national security team had advised in a memo in March 2008. It was counsel that only reinforced the president’s instincts.

Even before he was sworn in, Mr. Obama’s advisers had warned him against taking a categorical position on what would be done with Guantánamo detainees. The deft insertion of some wiggle words in the president’s order showed that the advice was followed.

Some detainees would be transferred to prisons in other countries, or released, it said. Some would be prosecuted — if “feasible” — in criminal courts. Military commissions, which Mr. Obama had criticized, were not mentioned — and thus not ruled out.

As for those who could not be transferred or tried but were judged too dangerous for release? Their “disposition” would be handled by “lawful means, consistent with the national security and foreign policy interests of the United States and the interests of justice.”

A few sharp-eyed observers inside and outside the government understood what the public did not. Without showing his hand, Mr. Obama had preserved three major policies — rendition, military commissions and indefinite detention — that have been targets of human rights groups since the 2001 terrorist attacks.

But a year later, with Congress trying to force him to try all terrorism suspects using revamped military commissions, he deployed his legal skills differently — to preserve trials in civilian courts.

It was shortly after Dec. 25, 2009, following a close call in which a Qaeda-trained operative named Umar Farouk Abdulmutallab had boarded a Detroit-bound airliner with a bomb sewn into his underwear.

Mr. Obama was taking a drubbing from Republicans over the government’s decision to read the suspect his rights, a prerequisite for bringing criminal charges against him in civilian court.

The president “seems to think that if he gives terrorists the rights of Americans, lets them lawyer up and reads them their Miranda rights, we won’t be at war,” former Vice President Dick Cheney charged.

Sensing vulnerability on both a practical and political level, the president summoned his attorney general, Eric H. Holder Jr., to the White House.

F.B.I. agents had questioned Mr. Abdulmutallab for 50 minutes and gained valuable intelligence before giving him the warning. They had relied on a 1984 case called New York v. Quarles, in which the Supreme Court ruled that statements made by a suspect in response to urgent public safety questions — the case involved the location of a gun — could be introduced into evidence even if the suspect had not been advised of the right to remain silent.

Mr. Obama, who Mr. Holder said misses the legal profession, got into a colloquy with the attorney general. How far, he asked, could Quarles be stretched? Mr. Holder felt that in terrorism cases, the court would allow indefinite questioning on a fairly broad range of subjects.

Tribesmen protested in Islamabad, the Pakistani capital, against ties with the United States, just days after President Obama took office in January 2009.
Tribesmen protested in Islamabad, the Pakistani capital, against ties with the United States, just days after President Obama took office in January 2009.Credit…Emilio Morenatti/Associated Press

Satisfied with the edgy new interpretation, Mr. Obama gave his blessing, Mr. Holder recalled.

“Barack Obama believes in options: ‘Maintain my options,’ “ said Jeh C. Johnson, a campaign adviser and now general counsel of the Defense Department.

‘They Must All Be Militants’

That same mind-set would be brought to bear as the president intensified what would become a withering campaign to use unmanned aircraft to kill Qaeda terrorists.

Just days after taking office, the president got word that the first strike under his administration had killed a number of innocent Pakistanis. “The president was very sharp on the thing, and said, ‘I want to know how this happened,’ “ a top White House adviser recounted.

In response to his concern, the C.I.A. downsized its munitions for more pinpoint strikes. In addition, the president tightened standards, aides say: If the agency did not have a “near certainty” that a strike would result in zero civilian deaths, Mr. Obama wanted to decide personally whether to go ahead.

The president’s directive reinforced the need for caution, counterterrorism officials said, but did not significantly change the program. In part, that is because “the protection of innocent life was always a critical consideration,” said Michael V. Hayden, the last C.I.A. director under President George W. Bush.

It is also because Mr. Obama embraced a disputed method for counting civilian casualties that did little to box him in. It in effect counts all military-age males in a strike zone as combatants, according to several administration officials, unless there is explicit intelligence posthumously proving them innocent.

Counterterrorism officials insist this approach is one of simple logic: people in an area of known terrorist activity, or found with a top Qaeda operative, are probably up to no good. “Al Qaeda is an insular, paranoid organization — innocent neighbors don’t hitchhike rides in the back of trucks headed for the border with guns and bombs,” said one official, who requested anonymity to speak about what is still a classified program.

This counting method may partly explain the official claims of extraordinarily low collateral deaths. In a speech last year Mr. Brennan, Mr. Obama’s trusted adviser, said that not a single noncombatant had been killed in a year of strikes. And in a recent interview, a senior administration official said that the number of civilians killed in drone strikes in Pakistan under Mr. Obama was in the “single digits” — and that independent counts of scores or hundreds of civilian deaths unwittingly draw on false propaganda claims by militants.

But in interviews, three former senior intelligence officials expressed disbelief that the number could be so low. The C.I.A. accounting has so troubled some administration officials outside the agency that they have brought their concerns to the White House. One called it “guilt by association” that has led to “deceptive” estimates of civilian casualties.

“It bothers me when they say there were seven guys, so they must all be militants,” the official said. “They count the corpses and they’re not really sure who they are.”

‘A No-Brainer’

About four months into his presidency, as Republicans accused him of reckless naïveté on terrorism, Mr. Obama quickly pulled together a speech defending his policies. Standing before the Constitution at the National Archives in Washington, he mentioned Guantánamo 28 times, repeating his campaign pledge to close the prison.

But it was too late, and his defensive tone suggested that Mr. Obama knew it. Though President George W. Bush and Senator John McCain, the 2008 Republican candidate, had supported closing the Guantánamo prison, Republicans in Congress had reversed course and discovered they could use the issue to portray Mr. Obama as soft on terrorism.

Gen. James L. Jones
Gen. James L. JonesCredit…Gerald Herbert/Associated Press

Walking out of the Archives, the president turned to his national security adviser at the time, Gen. James L. Jones, and admitted that he had never devised a plan to persuade Congress to shut down the prison.

“We’re never going to make that mistake again,” Mr. Obama told the retired Marine general.

General Jones said the president and his aides had assumed that closing the prison was “a no-brainer — the United States will look good around the world.” The trouble was, he added, “nobody asked, ‘O.K., let’s assume it’s a good idea, how are you going to do this?’ “

It was not only Mr. Obama’s distaste for legislative backslapping and arm-twisting, but also part of a deeper pattern, said an administration official who has watched him closely: the president seemed to have “a sense that if he sketches a vision, it will happen — without his really having thought through the mechanism by which it will happen.”

In fact, both Secretary of State Hillary Rodham Clinton and the attorney general, Mr. Holder, had warned that the plan to close the Guantánamo prison was in peril, and they volunteered to fight for it on Capitol Hill, according to officials. But with Mr. Obama’s backing, his chief of staff, Rahm Emanuel, blocked them, saying health care reform had to go first.

When the administration floated a plan to transfer from Guantánamo to Northern Virginia two Uighurs, members of a largely Muslim ethnic minority from China who are considered no threat to the United States, Virginia Republicans led by Representative Frank R. Wolf denounced the idea. The administration backed down.

That show of weakness doomed the effort to close Guantánamo, the same administration official said. “Lyndon Johnson would have steamrolled the guy,” he said. “That’s not what happened. It’s like a boxing match where a cut opens over a guy’s eye.”

The Use of Force

It is the strangest of bureaucratic rituals: Every week or so, more than 100 members of the government’s sprawling national security apparatus gather, by secure video teleconference, to pore over terrorist suspects’ biographies and recommend to the president who should be the next to die.

This secret “nominations” process is an invention of the Obama administration, a grim debating society that vets the PowerPoint slides bearing the names, aliases and life stories of suspected members of Al Qaeda’s branch in Yemen or its allies in Somalia’s Shabab militia.

The video conferences are run by the Pentagon, which oversees strikes in those countries, and participants do not hesitate to call out a challenge, pressing for the evidence behind accusations of ties to Al Qaeda.

“What’s a Qaeda facilitator?” asked one participant, illustrating the spirit of the exchanges. “If I open a gate and you drive through it, am I a facilitator?” Given the contentious discussions, it can take five or six sessions for a name to be approved, and names go off the list if a suspect no longer appears to pose an imminent threat, the official said. A parallel, more cloistered selection process at the C.I.A. focuses largely on Pakistan, where that agency conducts strikes.

The nominations go to the White House, where by his own insistence and guided by Mr. Brennan, Mr. Obama must approve any name. He signs off on every strike in Yemen and Somalia and also on the more complex and risky strikes in Pakistan — about a third of the total.

Aides say Mr. Obama has several reasons for becoming so immersed in lethal counterterrorism operations. A student of writings on war by Augustine and Thomas Aquinas, he believes that he should take moral responsibility for such actions. And he knows that bad strikes can tarnish America’s image and derail diplomacy.

Dennis C. Blair, former director of national intelligence.
Dennis C. Blair, former director of national intelligence.Credit…Doug Mills/The New York Times

“He realizes this isn’t science, this is judgments made off of, most of the time, human intelligence,” said Mr. Daley, the former chief of staff. “The president accepts as a fact that a certain amount of screw-ups are going to happen, and to him, that calls for a more judicious process.”

But the control he exercises also appears to reflect Mr. Obama’s striking self-confidence: he believes, according to several people who have worked closely with him, that his own judgment should be brought to bear on strikes.

Asked what surprised him most about Mr. Obama, Mr. Donilon, the national security adviser, answered immediately: “He’s a president who is quite comfortable with the use of force on behalf of the United States.”

In fact, in a 2007 campaign speech in which he vowed to pull the United States out of Iraq and refocus on Al Qaeda, Mr. Obama had trumpeted his plan to go after terrorist bases in Pakistan — even if Pakistani leaders objected. His rivals at the time, including Mitt Romney, Joseph R. Biden Jr. and Mrs. Clinton, had all pounced on what they considered a greenhorn’s campaign bluster. (Mr. Romney said Mr. Obama had become “Dr. Strangelove.”)

In office, however, Mr. Obama has done exactly what he had promised, coming quickly to rely on the judgment of Mr. Brennan.

Mr. Brennan, a son of Irish immigrants, is a grizzled 25-year veteran of the C.I.A. whose work as a top agency official during the brutal interrogations of the Bush administration made him a target of fierce criticism from the left. He had been forced, under fire, to withdraw his name from consideration to lead the C.I.A. under Mr. Obama, becoming counterterrorism chief instead.

Some critics of the drone strategy still vilify Mr. Brennan, suggesting that he is the C.I.A.’s agent in the White House, steering Mr. Obama to a targeted killing strategy. But in office, Mr. Brennan has surprised many former detractors by speaking forcefully for closing Guantánamo and respecting civil liberties.

Harold H. Koh, for instance, as dean of Yale Law School was a leading liberal critic of the Bush administration’s counterterrorism policies. But since becoming the State Department’s top lawyer, Mr. Koh said, he has found in Mr. Brennan a principled ally.

“If John Brennan is the last guy in the room with the president, I’m comfortable, because Brennan is a person of genuine moral rectitude,” Mr. Koh said. “It’s as though you had a priest with extremely strong moral values who was suddenly charged with leading a war.”

The president values Mr. Brennan’s experience in assessing intelligence, from his own agency or others, and for the sobriety with which he approaches lethal operations, other aides say.

“The purpose of these actions is to mitigate threats to U.S. persons’ lives,” Mr. Brennan said in an interview. “It is the option of last recourse. So the president, and I think all of us here, don’t like the fact that people have to die. And so he wants to make sure that we go through a rigorous checklist: The infeasibility of capture, the certainty of the intelligence base, the imminence of the threat, all of these things.”

Yet the administration’s very success at killing terrorism suspects has been shadowed by a suspicion: that Mr. Obama has avoided the complications of detention by deciding, in effect, to take no prisoners alive. While scores of suspects have been killed under Mr. Obama, only one has been taken into American custody, and the president has balked at adding new prisoners to Guantánamo.

The cleric Anwar al-Awlaki, who coached Umar Farouk Abdulmutallab in his plot to blow up an American airliner over Detroit.
The cleric Anwar al-Awlaki, who coached Umar Farouk Abdulmutallab in his plot to blow up an American airliner over Detroit.Credit…Site Intelligence, via European Pressphoto Agency

“Their policy is to take out high-value targets, versus capturing high-value targets,” said Senator Saxby Chambliss of Georgia, the top Republican on the intelligence committee. “They are not going to advertise that, but that’s what they are doing.”

Mr. Obama’s aides deny such a policy, arguing that capture is often impossible in the rugged tribal areas of Pakistan and Yemen and that many terrorist suspects are in foreign prisons because of American tips. Still, senior officials at the Justice Department and the Pentagon acknowledge that they worry about the public perception.

“We have to be vigilant to avoid a no-quarter, or take-no-prisoners policy,” said Mr. Johnson, the Pentagon’s chief lawyer.

Trade-Offs

The care that Mr. Obama and his counterterrorism chief take in choosing targets, and their reliance on a precision weapon, the drone, reflect his pledge at the outset of his presidency to reject what he called the Bush administration’s “false choice between our safety and our ideals.”

But he has found that war is a messy business, and his actions show that pursuing an enemy unbound by rules has required moral, legal and practical trade-offs that his speeches did not envision.

One early test involved Baitullah Mehsud, the leader of the Pakistani Taliban. The case was problematic on two fronts, according to interviews with both administration and Pakistani sources.

The C.I.A. worried that Mr. Mehsud, whose group then mainly targeted the Pakistan government, did not meet the Obama administration’s criteria for targeted killing: he was not an imminent threat to the United States. But Pakistani officials wanted him dead, and the American drone program rested on their tacit approval. The issue was resolved after the president and his advisers found that he represented a threat, if not to the homeland, to American personnel in Pakistan.

Then, in August 2009, the C.I.A. director, Leon E. Panetta, told Mr. Brennan that the agency had Mr. Mehsud in its sights. But taking out the Pakistani Taliban leader, Mr. Panetta warned, did not meet Mr. Obama’s standard of “near certainty” of no innocents being killed. In fact, a strike would certainly result in such deaths: he was with his wife at his in-laws’ home.

“Many times,” General Jones said, in similar circumstances, “at the 11th hour we waved off a mission simply because the target had people around them and we were able to loiter on station until they didn’t.”

But not this time. Mr. Obama, through Mr. Brennan, told the C.I.A. to take the shot, and Mr. Mehsud was killed, along with his wife and, by some reports, other family members as well, said a senior intelligence official.

The attempted bombing of an airliner a few months later, on Dec. 25, stiffened the president’s resolve, aides say. It was the culmination of a series of plots, including the killing of 13 people at Fort Hood, Tex. by an Army psychiatrist who had embraced radical Islam.

Mr. Obama is a good poker player, but he has a tell when he is angry. His questions become rapid-fire, said his attorney general, Mr. Holder. “He’ll inject the phrase, ‘I just want to make sure you understand that.’ “ And it was clear to everyone, Mr. Holder said, that he was simmering about how a 23-year-old bomber had penetrated billions of dollars worth of American security measures.

Mr. Abdulmutallab
Mr. AbdulmutallabCredit…United States Marshals Service

When a few officials tentatively offered a defense, noting that the attack had failed because the terrorists were forced to rely on a novice bomber and an untested formula because of stepped-up airport security, Mr. Obama cut them short.

“Well, he could have gotten it right and we’d all be sitting here with an airplane that blew up and killed over a hundred people,” he said, according to a participant. He asked them to use the close call to imagine in detail the consequences if the bomb had detonated. In characteristic fashion, he went around the room, asking each official to explain what had gone wrong and what needed to be done about it.

“After that, as president, it seemed like he felt in his gut the threat to the United States,” said Michael E. Leiter, then director of the National Counterterrorism Center. “Even John Brennan, someone who was already a hardened veteran of counterterrorism, tightened the straps on his rucksack after that.”

David Axelrod, the president’s closest political adviser, began showing up at the “Terror Tuesday” meetings, his unspeaking presence a visible reminder of what everyone understood: a successful attack would overwhelm the president’s other aspirations and achievements.

In the most dramatic possible way, the Fort Hood shootings in November and the attempted Christmas Day bombing had shown the new danger from Yemen. Mr. Obama, who had rejected the Bush-era concept of a global war on terrorism and had promised to narrow the American focus to Al Qaeda’s core, suddenly found himself directing strikes in another complicated Muslim country.

The very first strike under his watch in Yemen, on Dec. 17, 2009, offered a stark example of the difficulties of operating in what General Jones described as an “embryonic theater that we weren’t really familiar with.”

It killed not only its intended target, but also two neighboring families, and left behind a trail of cluster bombs that subsequently killed more innocents. It was hardly the kind of precise operation that Mr. Obama favored. Videos of children’s bodies and angry tribesmen holding up American missile parts flooded You Tube, fueling a ferocious backlash that Yemeni officials said bolstered Al Qaeda.

The sloppy strike shook Mr. Obama and Mr. Brennan, officials said, and once again they tried to impose some discipline.

In Pakistan, Mr. Obama had approved not only “personality” strikes aimed at named, high-value terrorists, but “signature” strikes that targeted training camps and suspicious compounds in areas controlled by militants.

But some State Department officials have complained to the White House that the criteria used by the C.I.A. for identifying a terrorist “signature” were too lax. The joke was that when the C.I.A. sees “three guys doing jumping jacks,” the agency thinks it is a terrorist training camp, said one senior official. Men loading a truck with fertilizer could be bombmakers — but they might also be farmers, skeptics argued.

Now, in the wake of the bad first strike in Yemen, Mr. Obama overruled military and intelligence commanders who were pushing to use signature strikes there as well.

“We are not going to war with Yemen,” he admonished in one meeting, according to participants.

His guidance was formalized in a memo by General Jones, who called it a “governor, if you will, on the throttle,” intended to remind everyone that “one should not assume that it’s just O.K. to do these things because we spot a bad guy somewhere in the world.”

Iraqis listened to Mr. Obama’s speech from Cairo in June 2009, intended to reach out to the Muslim world.
Iraqis listened to Mr. Obama’s speech from Cairo in June 2009, intended to reach out to the Muslim world.Credit…Moises Saman for The New York Times

Mr. Obama had drawn a line. But within two years, he stepped across it. Signature strikes in Pakistan were killing a large number of terrorist suspects, even when C.I.A. analysts were not certain beforehand of their presence. And in Yemen, roiled by the Arab Spring unrest, the Qaeda affiliate was seizing territory.

Today, the Defense Department can target suspects in Yemen whose names they do not know. Officials say the criteria are tighter than those for signature strikes, requiring evidence of a threat to the United States, and they have even given them a new name — TADS, for Terrorist Attack Disruption Strikes. But the details are a closely guarded secret — part of a pattern for a president who came into office promising transparency.

The Ultimate Test

On that front, perhaps no case would test Mr. Obama’s principles as starkly as that of Anwar al-Awlaki, an American-born cleric and Qaeda propagandist hiding in Yemen, who had recently risen to prominence and had taunted the president by name in some of his online screeds.

The president “was very interested in obviously trying to understand how a guy like Awlaki developed,” said General Jones. The cleric’s fiery sermons had helped inspire a dozen plots, including the shootings at Fort Hood. Then he had gone “operational,” plotting with Mr. Abdulmutallab and coaching him to ignite his explosives only after the airliner was over the United States.

That record, and Mr. Awlaki’s calls for more attacks, presented Mr. Obama with an urgent question: Could he order the targeted killing of an American citizen, in a country with which the United States was not at war, in secret and without the benefit of a trial?

The Justice Department’s Office of Legal Counsel prepared a lengthy memo justifying that extraordinary step, asserting that while the Fifth Amendment’s guarantee of due process applied, it could be satisfied by internal deliberations in the executive branch.

Mr. Obama gave his approval, and Mr. Awlaki was killed in September 2011, along with a fellow propagandist, Samir Khan, an American citizen who was not on the target list but was traveling with him.

If the president had qualms about this momentous step, aides said he did not share them. Mr. Obama focused instead on the weight of the evidence showing that the cleric had joined the enemy and was plotting more terrorist attacks.

“This is an easy one,” Mr. Daley recalled him saying, though the president warned that in future cases, the evidence might well not be so clear.

In the wake of Mr. Awlaki’s death, some administration officials, including the attorney general, argued that the Justice Department’s legal memo should be made public. In 2009, after all, Mr. Obama had released Bush administration legal opinions on interrogation over the vociferous objections of six former C.I.A. directors.

This time, contemplating his own secrets, he chose to keep the Awlaki opinion secret.

“Once it’s your pop stand, you look at things a little differently,” said Mr. Rizzo, the C.I.A.’s former general counsel.

Mr. Hayden, the former C.I.A. director and now an adviser to Mr. Obama’s Republican challenger, Mr. Romney, commended the president’s aggressive counterterrorism record, which he said had a “Nixon to China” quality. But, he said, “secrecy has its costs” and Mr. Obama should open the strike strategy up to public scrutiny.

About four months into his term, President Obama pulled together a speech defending his policies. Standing before the Constitution at the National Archives in Washington, he mentioned Guantánamo 28 times, repeating his campaign pledge to close the prison.

“This program rests on the personal legitimacy of the president, and that’s not sustainable,” Mr. Hayden said. “I have lived the life of someone taking action on the basis of secret O.L.C. memos, and it ain’t a good life. Democracies do not make war on the basis of legal memos locked in a D.O.J. safe.”

Tactics Over Strategy

In his June 2009 speech in Cairo, aimed at resetting relations with the Muslim world, Mr. Obama had spoken eloquently of his childhood years in Indonesia, hearing the call to prayer “at the break of dawn and the fall of dusk.”

“The United States is not — and never will be — at war with Islam,” he declared.

But in the months that followed, some officials felt the urgency of counterterrorism strikes was crowding out consideration of a broader strategy against radicalization. Though Mrs. Clinton strongly supported the strikes, she complained to colleagues about the drones-only approach at Situation Room meetings, in which discussion would focus exclusively on the pros, cons and timing of particular strikes.

At their weekly lunch, Mrs. Clinton told the president she thought there should be more attention paid to the root causes of radicalization, and Mr. Obama agreed. But it was September 2011 before he issued an executive order setting up a sophisticated, interagency war room at the State Department to counter the jihadi narrative on an hour-by-hour basis, posting messages and video online and providing talking points to embassies.

Mr. Obama was heartened, aides say, by a letter discovered in the raid on Osama bin Laden’s compound in Pakistan. It complained that the American president had undermined Al Qaeda’s support by repeatedly declaring that the United States was at war not with Islam, but with the terrorist network. “We must be doing a good job,” Mr. Obama told his secretary of state.

Moreover, Mr. Obama’s record has not drawn anything like the sweeping criticism from allies that his predecessor faced. John B. Bellinger III, a top national security lawyer under the Bush administration, said that was because Mr. Obama’s liberal reputation and “softer packaging” have protected him. “After the global outrage over Guantánamo, it’s remarkable that the rest of the world has looked the other way while the Obama administration has conducted hundreds of drone strikes in several different countries, including killing at least some civilians,” said Mr. Bellinger, who supports the strikes.

By withdrawing from Iraq and preparing to withdraw from Afghanistan, Mr. Obama has refocused the fight on Al Qaeda and hugely reduced the death toll both of American soldiers and Muslim civilians. But in moments of reflection, Mr. Obama may have reason to wonder about unfinished business and unintended consequences.

His focus on strikes has made it impossible to forge, for now, the new relationship with the Muslim world that he had envisioned. Both Pakistan and Yemen are arguably less stable and more hostile to the United States than when Mr. Obama became president.

Justly or not, drones have become a provocative symbol of American power, running roughshod over national sovereignty and killing innocents. With China and Russia watching, the United States has set an international precedent for sending drones over borders to kill enemies.

Mr. Blair, the former director of national intelligence, said the strike campaign was dangerously seductive. “It is the politically advantageous thing to do — low cost, no U.S. casualties, gives the appearance of toughness,” he said. “It plays well domestically, and it is unpopular only in other countries. Any damage it does to the national interest only shows up over the long term.”

But Mr. Blair’s dissent puts him in a small minority of security experts. Mr. Obama’s record has eroded the political perception that Democrats are weak on national security. No one would have imagined four years ago that his counterterrorism policies would come under far more fierce attack from the American Civil Liberties Union than from Mr. Romney.

Aides say that Mr. Obama’s choices, though, are not surprising. The president’s reliance on strikes, said Mr. Leiter, the former head of the National Counterterrorism Center, “is far from a lurid fascination with covert action and special forces. It’s much more practical. He’s the president. He faces a post-Abdulmutallab situation, where he’s being told people might attack the United States tomorrow.”