forthcoming 2016 U.S. presidential election, the Iranians wondered what would happen if the GOP took the White House. I would answer by asking them a similar question: “What if hard-liners opposed to the deal regained power in Iran?” It usually ended the discussion, as I thought it should: after all, I always expected that the greatest challenge to the deal’s success would be violations by Iran, not the political machinations of the president of the United States.

Of course, I was wrong. In May of this year, U.S. President Donald Trump decided to pull the United States out of the agreement and reimpose the U.S. sanctions on Iran that the deal had lifted, a move that will go down as one of the worst foreign policy blunders in U.S. history. The Iran deal was not perfect; no deal ever is. Nonetheless, the Joint Comprehensive Plan of Action (JCPOA), as the agreement is formally known, offered the best possible assurance that Iran would never obtain a nuclear weapon.

I don’t know if the Iran deal can survive the reinstatement of sanctions, which the United States set aside in exchange for the Iranians’ pledge to vastly reduce their uranium enrichment, produce no weapons-grade plutonium, and allow international inspectors to rigorously verify their compliance. The JCPOA’s restrictions close every possible path for Iran to obtain fissile material for a nuclear weapon. Although some of the restrictions that the deal places on Iran end after 10, 15, 20, or 25 years, its prohibition on Iran’s obtaining a nuclear weapon never ends. So far, the Iranians have stuck to the terms of the deal.

Trump’s decision has shaken the world’s faith in the United States’ commitment to multilateral diplomacy. No matter how much Trump

derides the deal, the JCPOA stands as a model for combining the threat of sanctions and continued isolation with the hard work of negotiating, even between countries whose

relationships are shaped by conflict and distrust. Before Trump undercut it, the JCPOA was advancing U.S. interests and making the world safer. Far from being “the worst deal ever,” as Trump likes to say, it represents a model that his administration should emulate as it negotiates with North Korea over its nuclear arsenal. In that situation, Trump has relied mostly on threats, bluster, and rosy pronouncements. But as he and his team are learning, direct talks with adversaries are difficult. They require courage, persistence, and a realistic sense of one’s own power.

Trump’s policies often seem to follow little logic other than to do the opposite of what (Barack) Obama did, no matter the circumstance and no matter the consequences. In this sense, his exit from the JCPOA was always a fait accompli. The deal had survived as long as it did thanks only to some of Trump’s early advisers, who understood its value. But they hadn’t lasted long in the chaos of the Trump administration.

With the hawkish John Bolton now driving Iran policy as Trump’s national security adviser and the president seeming to want to ingratiate himself with Israel and Saudi Arabia, the administration appears to have replaced the Iran deal with a threat of violent regime change.