In an interview with his biographer Michael D’Antonio, Donald Trump explained that although he received a medical deferment rather than serving in the war in Vietnam, “I always felt that I was in the military.” This was, as D’Antonio reported in “Never Enough: Donald Trump and the Pursuit of Success,” because he spent his high-school years at a military-themed boarding school, not far from West Point.

Last Saturday, President Trump trumpeted his military expertise during a visit to the C.I.A.’s headquarters, in Langley, Virginia, where he praised his nominee to direct the C.I.A., Michael Pompeo, for being first in his class at West Point. Then he digressed, noting, “I know a lot about West Point. . . . Trust me, I’m, like, a smart person.”

One difference between serving in the military and being a pretend soldier at the New York Military Academy, where Trump proudly led mock drills in snappy faux military uniforms, is that, in the real thing, officers are drilled not just in marching formations but also in the laws of war. These include the Geneva Conventions and the Convention Against Torture, which impose absolute, unconditional bans on torture and other forms of cruel and inhumane treatment of enemy combatants, categorizing such conduct, under any and all circumstances, as a war crime.

In an interview with ABC’s David Muir, made available on Wednesday, Trump gave a cursory nod to those laws. Asked if he wanted U.S. forces to use waterboarding, the President said that he would listen to his advisers, but that he wanted to do everything “within the bounds of what you’re allowed to do legally” to “fight fire with fire.” He told Muir, “I have spoken, as recently as twenty-four hours ago, with people at the highest level of intelligence, and I asked them the question: Does it work? Does torture work? And the answer was yes, absolutely.” He added, with emphasis, “Do I feel it works? Absolutely I feel it works.”

The interview came on the same day that several news organizations published a draft executive order that, if signed, would command the Trump Administration to review the possibility of reintroducing C.I.A.-run “black site” detention camps for terror suspects and the use of brutal interrogation techniques. These practices were used during the early years of the War on Terror, but were shut down after the Supreme Court declared them subject to prosecution. At the daily White House press briefing on Wednesday, Trump’s press secretary, Sean Spicer, described the draft as “not a White House document.” Still, it was circulating through high levels of the government, and President Trump’s sentiments were clear.

As any military expert could tell Trump, torture only increases the danger that soldiers face. It produces false intelligence, increases the risk that captured soldiers will themselves be tortured, and undermines discipline and moral authority. This is a lesson that George Washington knew well. As a general in the Revolutionary War, he vowed that, unlike the British, who tortured their captives, this new country would distinguish itself by its humanity toward enemy combatants. Washington’s order proved not just moral but also practical. As David Hackett Fischer wrote in “Washington’s Crossing,” his Pulitzer Prize-winning history, Washington’s superior treatment of enemy captives fomented desertion among British and Hessian soldiers, and bolstered the American soldiers’ morale.

Washington’s enlightened orders formed the backbone of U.S. military policy until the War on Terror. America didn’t always live up to these ideals, but it nonetheless valued them, and enshrined them in law. The original copies of the Geneva Conventions are kept in a safe at the State Department, signed by, among others, Winston Churchill, whose bust Trump reportedly has chosen to give a place of honor in his Oval Office.

The horrifying consequences of abandoning the high road are catalogued in the Senate Select Committee on Intelligence’s 2014 report on the C.I.A.’s use of torture during the Bush era. Daniel J. Jones, the congressional staff member who was the lead author of the Senate report, told me that, should Trump choose to read it, he would see that "it clearly details how the C.I.A. internally came to the conclusion that their interrogation program was ineffective—and that the C.I.A. should not be operating detention sites."

As Trump readily admits, he doesn’t feel he has time to read anything lengthy, which would seem to preclude his absorption of the five-hundred-page declassified summary of the Senate report, not to mention the six-thousand-seven-hundred-page classified original. It doesn’t help, either, that the Obama Administration, in deference to the wishes of the C.I.A., declined to hold anyone in the intelligence community accountable for the Bush-era torture program. Obama instead chose to, as he put it, “turn the page.” Unfortunately, that has made it all too easy for a new Administration to look to the old playbook. These missteps, Jones said, “are just dumbfounding.”

Luckily, if Trump were to sign the draft executive order, the decision on whether to return to the brutal detention and interrogation techniques that former Vice-President Cheney called “the dark side” would not be made by the President alone. According to the draft, it would be made in consultation with the Defense Secretary, the Attorney General, and various leaders of the intelligence community. Congress and the courts have major roles to play as well. And, while Trump may have missed the lessons of recent history, several of his top appointees are not just well informed but also have personal experience in this area.

As the Times reported, James Mattis, Trump’s Defense Secretary, like virtually every American military leader, is deeply opposed to the use of torture and the mistreatment of enemy combatants. As a Major General in Iraq, Mattis oversaw the swift court martial of U.S. marines under his command who had killed a captured suspect during a brutal interrogation. Trump seemed amazed to learn of Mattis’s opposition to torture, telling the Times, during a meeting with editors and reporters, that Mattis had told him that a beer and a pack of cigarettes work better. Trump’s surprise was itself a surprise to anyone with a modicum of understanding of American military history.

Daniel Coats, Trump’s choice for National Intelligence director, has also had a first-hand look at the costs of the C.I.A.’s former detention and interrogation program. He served as George W. Bush’s Ambassador to Germany, and had to explain to Germany’s Interior Minister, Otto Schily, that the C.I.A. had made an embarrassing mistake: it had “renditioned”—meaning kidnapped—the wrong German, whisking him to a secret black-prison site and physically tormenting him for five months. Coats convinced Schily not to press charges, and to keep the intelligence fiasco secret, but, after being freed, the mistaken suspect, Khalid El-Masri, won a suit in the European Court of Human Rights, in Strasbourg. The court found that he had been tortured, publicly shaming the C.I.A., and condemned the countries that had assisted in the secret program.

Scott Horton, a human-rights lawyer and advocate, predicts that reopening the C.I.A.’s program would present huge legal issues. “I think they would do whatever they can to keep it out of the federal courts, but it's likely they'd face troubles trying to do this anywhere in Europe. North Africa and the Middle East are another question. Where would Trump put these black sites? Morocco, Egypt, and Israel would be the logical candidates,” he said. He also noted that “NATO is already under heavy pressure by Trump, but the black-site regime will again test NATO's relationship with the U.S. Previously, Hungary, Poland, Lithuania, and Romania were among the nations providing cover for C.I.A. torture and ‘disappeared’ imprisonment. Will they be challenged to do this again?”

The answer is no, if John McCain, the Senate’s best-known military hero, has anything to say about it. Trump belittled McCain during the campaign for having been captured during the Vietnam War, but McCain now is in position to teach the President a thing or two about how real soldiers think. Using Trump’s favorite weapon—Twitter—McCain fired back, “@potus can sign whatever executive orders he likes, but the law is the law – we’re not bringing back torture.”