Illustration by Tom Bachtell

Long before Donald Trump was mocking “Little Rocket Man” in North Korea, or taunting “fools” in the Republican foreign-policy establishment, he expressed special contempt for one international agreement: the Joint Comprehensive Plan of Action, which blocked Iran from developing a nuclear weapon. After the Obama Administration signed the agreement, in 2015, then candidate Trump called it “the worst deal ever,” and vowed to “renegotiate” it once he was in office. In fact, the landmark agreement capitalized on a rare consensus. After years of hesitating, China and Russia joined the other permanent members of the United Nations Security Council, along with Germany and the European Union, in supporting American pressure on Iran to change course. At a negotiating session in Vienna, the coalition was so large that, for appearance’s sake, Iran stocked its side of the table with additional staffers. Jake Sullivan, one of the U.S. negotiators, recalled, “It was the whole world versus Iran.”

The deal did not change all of Iran’s bad behavior: Tehran continued to test conventional ballistic missiles, to foment violence in Iraq and Syria, and to unjustly detain Americans. But the effect on its nuclear program was unquestionable. In return for the removal of sanctions imposed by the United States and other nations, which had crippled its economy, Iran agreed to shut down facilities and to give broad access to inspectors from the International Atomic Energy Agency. Even fierce critics of Tehran, including U.S. Defense Secretary James Mattis and Ehud Barak, the former Israeli Prime Minister, have held the agreement to be vital to international security. Mohammad Javad Zarif, Iran’s foreign minister, and Federica Mogherini, the European Union’s foreign-affairs chief, were widely mentioned as contenders for this year’s Nobel Peace Prize.

When President Trump discovered that not only Mattis but also Secretary of State Rex Tillerson and other national-security officials wanted to preserve the agreement, “he threw a fit,” a source told the Washington Post last week. By early October, the White House had devised a plan to assuage his anger. The President would refuse to certify that the deal is in America’s national interest, an action that would not undo the agreement outright but punt the decision to Congress, for lawmakers to decide whether to renew sanctions.

It is a risky move, nonetheless. If hawks in Congress push through a law demanding further concessions, it could provoke Iran to abandon the deal, eject the inspectors, and accelerate its nuclear program. That might result in calls for Iran’s facilities to be destroyed before they can produce enough weapons-grade material for a bomb. Such a chain of events could lead to a particularly perilous consequence: returning to the possibility of military conflict with Iran, at a time when the United States is already facing a nuclear standoff with North Korea, would court the prospect of a two-front war—an act of self-sabotage more immediately damaging to American security than reviving the xenophobic slogan “America First,” withdrawing from the Paris climate accord, or antagonizing our allies (Mexico, Australia, South Korea, and counting).

Gutting a deal that Americans conceived, brokered, and secured would undercut decades of U.S. leadership on non-proliferation. Thomas Graham, Jr., a retired ambassador who worked in a senior capacity on every major American arms-control and disarmament negotiation over a period of twenty-five years, said of Trump’s comments about the Iran deal, “I’ve never seen anything remotely like this. There isn’t any reason in my opinion to decertify it, except for narrow political advantage, or if you really want to have a war. Historically, there was certainly opposition to some arms-control agreement, but this just seems like we’re reading Kafka.”

Indeed, in the past two weeks there have been a number of indicators of the President’s growing political instability. On October 7th, Trump, having ridiculed Tillerson for seeking a negotiated solution with North Korea, all but threatened an attack, tweeting, “Sorry, but only one thing will work!” Last week, NBC reported that, during a Pentagon briefing, Trump called for a nearly tenfold increase in the nuclear arsenal. National-security aides were unnerved—any such increase would violate a raft of disarmament treaties and set off a global arms race. (It was after this meeting that Tillerson reportedly called Trump a “fucking moron.”) The President and his aides denied the account, and he tweeted that it might be time to challenge NBC’s broadcast licenses.

Trump’s reflexive pursuit of manufactured conflict is becoming unbearable even to some of his most loyal erstwhile allies. Bob Corker, the chairman of the Senate Foreign Relations Committee, told the Times, “We could be heading towards World War III with the kinds of comments that he’s making.” Tom Barrack, one of Trump’s closest friends, told the Washington Post that he was “shocked” and “stunned” by the President’s rhetoric and tweets.

Decertifying the Iran agreement would fracture the United States’ credibility among its original partners in the deal. It would open a rift with China just as it is weighing whether to join the United States again, this time in negotiating with North Korea. Global Times, a state-backed Chinese newspaper, has asked, “If America would overturn a pact it made to the rest of the world, solely because of a transition in government, how can it retain the reputation of a great power?”

The harm to America’s full faith and credit would be particularly acute in Pyongyang. A decision to undermine the signature foreign-policy deal of a previous Administration would tilt the balance away from North Korean officials who argue for compromise. “The more hawkish cohorts will feel emboldened during internal deliberations against people in the diplomatic, intelligence, and economic communities,” Michael Madden, of Johns Hopkins University’s 38 North Web site, said.

A nation’s credibility is the type of asset that is easy to overlook, until an emergency makes it precious. During the Cuban missile crisis, in 1962, President John F. Kennedy dispatched former Secretary of State Dean Acheson to Paris to inform President Charles de Gaulle that the Administration had decided to stage a naval blockade of Cuba. Acheson offered to show surveillance photographs of the island’s missile sites, but de Gaulle waved them away, saying, “The word of the President of the United States is enough for me.” History suggests that President Trump’s disdain for even the achievements of his predecessor is most damaging not in the eyes of America’s enemies but in the eyes of its friends. ♦