Donald Trump failed to deliver a campaign vow to restore the post-9/11 practice of waterboarding suspects held in U.S. custody, according to available accounts.

An official policy change would require passage of a new law permitting waterboarding, plus an overhaul of President Barack Obama's executive order banning the practice. Trump has done neither. The interrogation method, which simulates the experience of drowning, remains illegal.

National security law experts and human rights groups told us there's also no evidence the practice is being carried out in secret.

"As far as we know, Trump hasn't brought back waterboarding," said Daphne Eviatar of Amnesty International USA.

An official at Human Rights Watch echoed this sentiment, but cautioned that monitoring groups have not been granted access to certain detainees, including those held at the U.S. military prison in Guantanamo Bay, Cuba.

In May, Trump's CIA director Gina Haspel promised lawmakers that the kinds of harsh interrogation methods employed after 9/11, which many believe to be torture, would not be revived on her watch.

"I can offer you my personal commitment, clearly and without reservation, that under my leadership CIA will not restart such a detention and interrogation program," Haspel said in her May 9, 2018, Senate confirmation hearing. She added that CIA interrogations would comply with the Army Field Manual, which prohibits waterboarding.

Karen Greenberg, an expert on torture and director of Fordham Law School's Center on National Security, said she believes the practice is consigned to the past.

"I think this is now a part of history. It's not part of the present — we've seen no evidence of that," she said. "There could be things going on, but it seems like a long step, and I don't think they're going down that road again."

Because Trump has failed to use legislative or executive means to restore waterboarding, and given that human rights groups have found no evidence it's being carried out in secret, we rate this Promise Broken.

Donald Trump's campaign trail promise to bring back waterboarding is at a standstill.

Since taking office, Trump has stepped back from the issue of interrogation methods, deferring to top advisers for guidance on how to handle enemy combatants in U.S. custody.

In his most recent comments on the matter, Trump said he would rely on his secretary of defense, former Marine Gen. James Mattis, about whether to reinstate the practice of waterboarding, which is illegal under current U.S. law.

"Mattis (has) stated publicly that he does not necessarily believe in torture or waterboarding," Trump said in a Jan. 27 press conference. "I don't necessarily agree, but I would tell you that he will override because I'm giving him that power."

During his confirmation process, Mattis told lawmakers that as Pentagon chief, all U.S. military interrogations would comply with the Army Field Manual, which is codified in U.S. law, and prohibits waterboarding and other so-called "enhanced interrogation techniques."

Earlier, Mattis told Trump "a pack of cigarettes and a couple of beers" worked better than torture.

If Trump relied solely on Mattis's input, waterboarding would remain verboten.

However, Trump has previously said he would defer to other members of his circle on the question of waterboarding, and specifically named CIA Director Mike Pompeo.

"I will rely on Pompeo and Mattis and my group," Trump said in a Jan. 25 interview with ABC News. "And if they don't want to do, that's fine. If they do want to do, then I will work for that end."

It's unclear if Trump intends to give equal weight to Mattis and Pompeo. But it's worth noting Mattis' vow to lawmakers referred only to interrogations carried out by the U.S. military, not intelligence operatives.

Pompeo's views on waterboarding are more ambiguous than Mattis'.

During Pompeo's confirmation hearing, he too reassured senators the CIA would comply with the Army Field Manual and would not conduct enhanced interrogation techniques, even at Trump's request.

But in subsequent written responses to senators' questions, Pompeo's position seemed more equivocal, and appeared to leave open the possibility of reviewing the agency's interrogation methods.

Sen. Dianne Feinstein, D-Calif., asked whether Pompeo would consider bringing waterboarding back to the CIA. Pompeo replied that he would consult with intelligence and other officials on whether the Army Field Manual's constraints posed "an impediment to gathering vital intelligence to protect the country."

"If experts believed current law was an impediment to gathering vital intelligence to protect the country," he wrote, "I would want to understand such impediments and whether any recommendations were appropriate for changing current law."

That provoked a stern rebuke from Human Rights Watch and others that have been outspoken in criticizing the application of harsh interrogation methods.

Pompeo's responses to questions about torture "are dangerously ambiguous about whether he would endorse abusive practices and seek to subvert existing legal protections," said Maria McFarland Sanchez-Moreno, who co-directs Human Rights Watch's U.S. program.

The CIA would not say whether Pompeo has reviewed the current law governing interrogation, or consulted with intelligence or other officials on the matter.

There's no sign Trump has taken direct action to bring back waterboarding. Rather, his most recent position is that he intends to rely on guidance from his defense secretary.

In earlier statements, however, Trump also said he would defer to his CIA director, who appears to be holding the door ajar for revisiting the law governing U.S. interrogation methods.

For these reasons, we rate Trump's promise as Stalled.

Donald Trump thinks the United States isn't demonstrating its strength enough in the fight against the Islamic State. One of his proposed solutions as president is to revive waterboarding, an enhanced interrogation technique that was used on terrorism suspects following the Sept. 11 attacks.

Barack Obama had officially discontinued the tactic because it simulates drowning and is considered to be a form of torture.

"I would bring back waterboarding, and I'd bring back a hell of a lot worse than waterboarding," he said at a Feb. 7, 2016, primary debate.

WHY HE'S PROMISING IT

The fact that terrorists know the United States doesn't waterboard puts the country at a disadvantage against the Islamic State, Trump has argued.

"They're chopping off heads and drowning people in big steel cages, and we can't waterboard, okay?" he said in an April 2016 interview with Fox News host Sean Hannity.

There is no concrete evidence that waterboarding is effective at extracting information. Further, there is scientific proof that techniques like waterboarding affect brain function in such a way that the person under interrogation is no longer reliable.

While Trump believes that waterboarding works, he has said that "if it doesn't work, they deserve it anyway, for what they're doing."

WHAT NEEDS TO HAPPEN

Torture is already illegal in the United States, but President George W. Bush's administration justified waterboarding and other enhanced interrogation tactics with legal maneuvering.

Amid the backlash against these interrogation practices, Obama banned specific interrogation tactics — including waterboarding — with an executive order in 2009, and Congress turned that executive order into law in 2015.

If the Trump administration wants to waterboard and do it legally, he would have to repeal Obama's executive order and get Congress to change the law. He also would have to find a way around international laws against torture, the constitutional ban on cruel and unusual punishment, and more, said Karen Greenberg, an expert on torture and director of Fordham Law School's Center on National Security.

She added that the United States currently does not detain and interrogate many high-value targets — they kill the targets instead — so reviving Bush-era enhanced interrogation would be irrelevant in that context.

WHAT'S STANDING IN HIS WAY

Beyond certain legal challenges Trump would face, there's plenty of political pressure against waterboarding. The law limiting enhanced interrogation had strong bipartisan support.

So there likely would be blowback from Republicans such as Sen. John McCain of Arizona, who said in November, "I don't give a damn what the president of the United States wants to do. We will not waterboard."

And Trump might also face resistance from career military and CIA agents, as well as lawyers from across the political spectrum who see waterboarding as indisputably illegal.

Mike Pence said he wouldn't rule out waterboarding as vice president, and Trump's pick to replace Brennan as CIA director, Rep. Mike Pompeo of Kansas, has said the post-9/11 enhanced interrogation tactics were lawful.

In the weeks after the election, Trump seemed to be less committed to his waterboarding promise, saying he was surprised to learn that his pick for secretary of defense, Ret. Marine Corps Gen. James Mattis, does not think waterboarding is a high priority.