What is waterboarding, and who believes it works?

Through the centuries, humans have demonstrated extraordinary inventiveness in finding ways to extract confessions from foes. One of the most enduring means of coercion, dating at least to the days of the Spanish Inquisition, is a method that was long known as water torture.

It comes down to the simplest of elements: air and water. And the most elemental of emotions: fear.

Now known colloquially as waterboarding, the tactic has hopscotched across conflicts and cultures. Once again, it has made the leap from medieval parchments to TV screens, as President Trump signals he may seek to revive its use.

In modern times, waterboarding is so named for the board, angled downward at the head, to which a subject is strapped before interrogation. When water is poured over the face, it creates the feeling that the lungs are filling with water, simulating an overpowering sensation of drowning.

Long before waterboarding was employed against suspects in the 9/11 attacks — most famously in the case of alleged mastermind Khalid Sheikh Mohammed, who was said to have undergone the tactic 183 times in a single month — American troops utilized a form of it in the Spanish-American War in the Philippines at the dawn of the 20^th century.

U.S.-allied South Vietnamese forces also did so more than half a century later. When Japanese troops were put on trial for war crimes after World War II, episodes of waterboarding were featured in tribunal transcripts. In the 1970s, the practice turned up in the fearsome prisons of Latin American dictators. The French utilized variants of it in Algeria; so did the British, in mandate Palestine.

During the Spanish Inquisition, water torture was one of an array of means of forcing unfortunates to confess to purportedly heretical thoughts and actions. By the 16^th century, the practice was codified in criminal law across continental Europe, a practice adhered to by “princes and kings and sovereign city-states and, sometimes, dioceses,” said University of Pennsylvania emeritus history professor Edward Peters.

Favored because it could inflict immense suffering without leaving a mark, water torture took the form of both simulated drowning and pumping water directly into the stomach. Peters cited a 16th century French text on criminal procedure with an illustration showing a practice “very similar” to waterboarding, including use of a thin cloth to cover the subject’s mouth while water was poured onto the face.

The late writer Christopher Hitchens, a self-described skeptic as to whether waterboarding was all that bad, once voluntarily submitted to a session of it at the hands of former military trainers who had schooled elite American troops in how to resist — not inflict — the practice.

“You feel that you are drowning because you are drowning — or rather, being drowned, albeit slowly and under controlled conditions and at the mercy (or otherwise) of those who are applying the pressure,” Hitchens wrote in a 2008 Vanity Fair piece headlined “Believe Me, It’s Torture.”

Initially holding his breath and then finally forced to draw one, Hitchens recounted that “the inhalation brought the damp cloths tight against my nostril, as if a huge, wet paw had been suddenly and annihilatingly clamped over my face.” The experience left him “unable to determine whether I was breathing in or out, and flooded more with sheer panic than with water.”

Human rights advocates — who hailed the Obama administration’s 2009 decision to outlaw the practice — have expressed horror over its potential return. In the current political context, though, argument about the practice turns not only on its morality, but its efficacy.

A landmark study by the Senate Intelligence Committee concluded that harsh interrogation methods including waterboarding did not result in obtaining crucial information that could not have been unearthed through other means. But that drew pushback from some current and past intelligence officials who defended tactics including waterboarding as having helped pinpoint Osama bin Laden’s location and the raid that killed the Al Qaeda leader.

Trump, who has gone back and forth on the issue, declared in a televised interview Wednesday night that he had asked high-level intelligence officials whether harsh interrogation methods — torture — in fact worked.

“And the answer was, ‘Yes, absolutely,’” the president told ABC News.

He added: “Do I feel it works? Absolutely, I feel it works.”

On Friday, Trump reiterated his views favoring harsh interrogation methods — but said he would defer to Defense Secretary James N. Mattis. The Pentagon this week reaffirmed that Mattis was committed to upholding the law against waterboarding.

“I happen to feel it does work,” Trump said, speaking at a news conference with visiting British Prime Minister Theresa May. But he pronounced Mattis “an expert” and added: “I’m going to rely on him.”

The new CIA director, Mike Pompeo, was reported to have been caught by surprise by the existence of a draft directive opening the door to reviving the use of torture. Pompeo had told Congress during confirmation hearings that he would oppose reintroducing methods such as waterboarding.

And U.S. Sen. John McCain, who underwent years of torture as a prisoner of war in Vietnam, has vowed to lead the fight against abusive interrogation practices.

“The president can sign whatever executive orders he likes,” the Arizona Republican said in a statement issued Wednesday by his office. “But the law is the law. We are not bringing back torture in the United States of America.”

Even if the directive goes forward, waterboarding’s usefulness as a tool continues to be sharply questioned.

Forensic psychologist Coral Dando, who specializes in the psychology of torture, wrote in Thursday’s editions of Britain’s Independent newspaper that in situations of extreme physical and psychological stress — such as waterboarding — “human cognitive processes begin to break down, sometimes irrevocably,” affecting decision-making and memory.

“Even if interrogators are 100 percent sure that a detainee knows the information being sought … coercive methods may in fact interfere with the quality and quantity of any information that might be forthcoming,” she wrote.

Naureen Shah, director of Amnesty International’s program on security and human rights, said she believed there would be a strong legal case for preventing any executive order from being implemented, not least because Obama’s ban on torture was codified by Congress, and waterboarding is explicitly prohibited by the Army Field Manual, used as an interrogation guidebook by U.S. personnel.

“By all first-hand descriptions, waterboarding is simulated death,” Shah said. “Only under a radical reinterpretation would it be considered anything other than torture.”

laura.king@latimes.com

@laurakingLAT

UPDATES:

11:45 a.m.: This article has been updated with comments Presidents Trump made Friday regarding the effectiveness of torture.

This article was originally published at 9 a.m.