Last weekend, President Donald Trump reportedly told the U.S. trade representative to scare South Korean negotiators by telling them he was a madman. “You tell [the South Koreans] if they don't give the concessions now, this crazy guy will pull out of the deal,” he said, referring to the U.S.-Korea free trade agreement. That report came at the end of a day in which the president’s tweets about another issue on the Korean peninsula evoked comparisons to the Nixon-era “madman theory” that you can scare an opponent into concessions by cultivating an image of recklessness. “I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man,” the president wrote. “… Save your energy Rex, we’ll do what needs to be done!”

Although President Trump credits himself with breaking every presidential norm, in choosing to intimidate foreign opponents through feigned (or real) recklessness, he is borrowing from the playbook of a predecessor. In April 1971, facing an impasse in negotiations with the North Vietnamese to end the Vietnam War, Richard Nixon gave Trump-like advice to his national-security adviser, Henry Kissinger. Kissinger had just suggested that he might hint to Hanoi, “if you think you’re going to defeat him [Nixon], if you don’t accept this [latest offer], he will stop at nothing”—implying the use of nuclear weapons.

Nixon: You can say, “I cannot control him.” Put it that way.

Kissinger: Yeah. And imply that you might use nuclear weapons.

Nixon: Yes, sir. “He will. I just want you to know he is not going to cave.”

Nor did Nixon invent this approach. Nixon’s mentor in foreign policy, Dwight Eisenhower’s secretary of state John Foster Dulles, was credited by many in Washington with having ended the Korean War by hinting to the Chinese that the former Allied commander was tough enough to use nuclear weapons in Korea. Even some top Democrats believed in this. According to Nixon’s autobiography, Lyndon B. Johnson, who was minority leader in the Senate when the war ended, later confessed to Nixon his belief that the Soviets “‘feared Ike’ because of what Dulles had threatened to do in Korea.” Eisenhower, of course, never allowed anyone to imply that he was crazy. But, in the expectation that the information would reach Mao, Dulles did hint to Indian Prime Minister Jawaharlal Nehru that the Eisenhower administration was prepared to widen the war if negotiations did not succeed. As Eisenhower biographer William Hitchcock has recently argued, this was a self-serving myth Dulles himself invented after the fact. Not only does post-Cold War evidence suggest that the hint had no effect on Chinese decision-making, there is no reason to believe it ever reached Beijing at all.

Unfortunately, fake history can be irresistible to some leaders, especially when it confirms their preconceptions more than what actually happened. Nixon and Kissinger, who referred respectfully to the “Dulles ploy,” not only seemed to accept the effectiveness of the nuclear ploy but added a very dangerous new twist to it. Nixon didn’t just want to convey Eisenhower toughness, but also that he could be reckless. In a conversation with his chief of staff H. R. “Bob” Haldeman, which Haldeman revealed in his memoir, Nixon described this new variant as the “Madman Theory.” According to Haldeman, the so-called theory was actually “a threat of egregious military action by an unpredictable U.S. President who hated Communism, coupled with generous offers of financial aid.”

There are very good reasons why, until Trump, Nixon was the only chief executive to have associated himself with such a strategy: It makes no sense for a confident, great power. Since Pearl Harbor, the United States has acted as a leading partner in grand alliances designed to defeat vicious adversaries and then maintain some semblance of international peace. Such alliances—whether the Big Three of World War II or the postwar North Atlantic Treaty Organization—are founded on trust that, to put it bluntly, you would take a bullet for the other guy. These don't work as well if the states at the helm, as personified by their leaders, are erratic or irrational. You cannot be both a reckless madman and a reliable alliance partner. Throughout the Cold War, for example, the U.S. worked hard to encourage non-nuclear allies like West Germany to accept “extended deterrence,” the idea that they did not need their own nukes because the United States could be relied upon to defend them. Nonproliferation, which is difficult in the best of times, becomes impossible if the foreign ally thinks the American president is erratic and untrustworthy. It is inconceivable that John F. Kennedy, Gerald Ford, or George H. W. Bush, for example, would have believed it useful for any foreign leader to think him “crazy.”

Back to Nixon. He and Kissinger understood the importance of NATO. Their madman game was narrowly focused on America’s adversaries, not its allies. And it was the product of desperation. Nixon had been elected promising to end the war in Vietnam. It wasn’t just congressional Democrats or anti-war demonstrators in the streets who wanted the United States to start withdrawing troops; Republicans, most notably Nixon’s secretary of defense Melvin Laird, believed that troop withdrawals were needed soon for the sake of domestic tranquility. Kissinger and Nixon worried that the domestic drumbeat for withdrawal would give Hanoi and incentive to stonewall in negotiations. Kissinger used the metaphor of “salted peanuts” to convey the idea that the desire for withdrawals would be uncontrollable once the American people got their first taste. Why would the North Vietnamese deal now, went the argument, when if they just waited the U.S. commitment to the war was bound to wind down and then collapse?

Enter the madman. Kissinger encouraged Nixon to undertake actions while there was still time—while they were still credible—to suggest he would stop at nothing to end the war in what he considered an honorable fashion.

Nixon and Kissinger came into office believing that the Vietnam War could be over by the end of 1969. All that was necessary was guts, toughness, and a thick skin at home, and Hanoi would be forced to make real concessions. “I have great sympathy for President Johnson as a patriot,” Nixon recorded himself saying as he thought retrospectively about the Vietnam War in April 1973, a few months after the U.S. signed a peace agreement with Hanoi. “He was surrounded by people who were soft-headed, worse.” After Vietnam launched an offensive for Tet 1969 (a year after its more famous Tet offensive), Nixon began the secret bombing of Cambodia. It didn’t stop the North Vietnamese from waging their war. In the summer of 1969, Kissinger convinced Nixon to double down, first offering a plan, “Duck Hook,” that in an early draft, according to the historians William Burr and Jeffrey Kimball, involved the use of nuclear weapons. In the end Nixon dropped the plan, but not before agreeing to a pointless fake nuclear alert in October 1969 designed to scare the Soviets into putting pressure on the North Vietnamese. Over the next two years, U.S. forces invaded Cambodia, then provided assistance to  a South Vietnamese offensive in Laos. Still the North Vietnamese did not cave.

By the summer of 1971, although Nixon did not stop talking privately about sending a signal of toughness, his focus shifted from trying to convince Hanoi that he was mad to finding ways to convince Beijing that he wasn’t, breaking a domestic political taboo to enlist Mao’s help in altering North Vietnamese behavior. The breakthrough with Hanoi finally came in October 1972, when the North Vietnamese for the first time agreed that the regime of Nguyen Van Thieu could remain in power in South Vietnam as part of a peace agreement with Washington. (This occurred after another round of action and reaction—North Vietnam’s Easter Offensive followed by a U.S. air campaign in April and the mining of Haiphong harbor in May.)

Nixon’s madman strategy wasn’t supposed to take three and a half years, over 21,000 U.S. deaths, and untold Vietnamese losses, to work. It was supposed to be a version of “shock and awe.” Until we see Hanoi’s decision-making records to be sure, the more likely explanation is that a combination of other factors led to Hanoi’s concession—namely the likelihood that Nixon would be re-elected (and yet would be more amenable to a negotiated settlement as a candidate for re-election) and the effects of Nixon’s opening to China and détente with the Kremlin.

There can be little debate, however, over what Nixon’s calculated unpredictability abroad achieved at home. It tore this country apart. In a declassified “eyes only” memorandum to Alexander Haig on May 20, 1972, after ordering the mining of Haiphong harbor, Nixon explained who his domestic audience was: “The hawks are our hard core and we must do everything that we can to keep them from jumping ship [in reaction to arms-control talks with Moscow] after getting their enthusiasm restored as a result of our mining operation in the North.” The madman approach was not just for Hanoi. Nixon wanted his base to know he was tough, thus distracting attention from his simultaneous efforts to build bridges to Hanoi’s communist patrons in the Kremlin and the Forbidden City.   

It is not surprising that Trump, who prides himself on being tougher than any adversary and who apparently has little interest in allies or diplomacy, would latch on to this theory of applied bullying. What is remarkable is that no one seems to have successfully gotten through to him that it is unlikely to work.

In the Nixon era, the logic of the madman theory, to the extent it was logical, was that a nuclear-armed superpower could effectively threaten a non-nuclear developing country. The U.S. would raise the cost of the war to a level that would be unacceptable to Hanoi. As it turned out, the U.S. was never really able to do this. And there is even less reason to assume it would work against North Korea in 2017. The U.S. is certainly stronger than North Korea, just as it was in comparison to North Vietnam, but North Vietnam did not itself have nuclear weapons; North Korea does. What is credible about the idea that the U.S. would risk a nuclear attack on Guam or Hawaii or, by mistake, Japan to get a chance at wiping out Pyongyang? Moreover, in the Vietnam War Nixon learned the hard way that if an adversary believes their existence is at stake, they are likely to fight even harder as you increase the pressure on them. Why, now, would North Korea react to Trump’s intentional recklessness by disarming, thus becoming even more vulnerable to U.S. power? It makes no sense.

The strategy might have a better chance at forcing concessions from non-nuclear allies, like South Korea. But here the costs would be of a different kind. For example, savvy U.S. trading partners are finding domestic American groups that would be hurt by Trumpian protectionism. There is a huge Kia plant in West Point, Georgia, whose Republican Congressman Drew Ferguson might not want to lose its 800 jobs. Similarly, Canadian companies have been in touch with members of Congress, such as the powerful head of the Freedom Caucus Mark Meadows, who represent areas where they employ U.S. citizens.

There is an aspect to Trump’s toying with the madman fallacy that makes it potentially even more threatening to peace and international tranquility than the Nixon effort. In light of Trump’s tweets, it is fair to assume that some of the president’s unpredictability is unrehearsed. Nixon had an unstable personality, but his risk-taking in Vietnam, however ill-founded, was at least plotted with Henry Kissinger.

Ultimately, Trump might find that he will be the biggest loser. In April 1973 Nixon, who shared the 45th president’s habit of saying unexpectedly revealing things, confessed to a visiting former POW, Lt. General John B. Flynn that there was a limit to how much presidential irrationality the American people could stomach: “We are never going to have a madman as president, in this office. We never have, probably never will have,” he said, according to a declassified recording he made of the conversation. “Ours [system] throws them out … about every four years, if a guy shows that he’s [unclear phrase], out!”

There is the intriguing possibility that Trump or his advisers got their fake history lesson about the madman theory from the venerable Henry Kissinger, who still loves giving presidents advice and appeared as an adviser of sorts to Trump after the election. Whatever the case, Kissinger would certainly be more useful to this president as an eyewitness to how Nixon ultimately got ensnared in his own madman delusion.