It took 15 months for President Trump to finally pull the trigger on the biggest foreign policy achievement of his predecessor. On May 8, four days before a deadline, he announced that the United States was withdrawing from the Joint Comprehensive Plan of Action and restoring all prior U.S. sanctions on Iran. While it will take several months to reimpose these penalties, there is little reason for optimism that the decision will produce a more coherent policy that constrains Iran’s nuclear program and regional interventions.

Trump insists that he can negotiate “better” deals than Barack Obama and other former presidents. In exiting the Iran deal, however, he is throwing away the leverage that only multinational action can bring. Apart from Israeli Prime Minister Benjamin Netanyahu and the untested crown princes of Saudi Arabia and the United Arab Emirates, there is no coalition of the willing behind this reckless act.

{mosads}Unfortunately, the decision was in keeping with Trump’s “America alone” instincts. One after another, he has withdrawn from laboriously negotiated international agreements, such as the Paris Climate Accord and the Trans Pacific Partnership, without providing viable alternatives. His vision of a “great” America appears to be one that builds up its military and constructs many walls, physical in the case of the U.S.-Mexico border and economic in the case of tariffs and sanctions. The rest of the world must try to get along somehow without the active cooperation of the biggest military and economic power.

Trump’s announcement, following futile visits to Washington by the presidents of France and Germany, and the British foreign secretary, will further undermine relations with Europe already strained by disputes over climate, trade and defense spending. Brussels and the big three nations of France, Germany and Italy have vowed to continue to uphold the JCPOA and may resort to legal measures to oppose secondary sanctions that lack the force and legitimacy of international law.

It will be interesting to see what impact Trump’s actions against Iran will have on his upcoming talks with the dictator of North Korea. Experts have told this analyst that Kim Jong Un is likely to stiffen his demands for benefits upfront in return for any concessions on his much more advanced nuclear program. That could easily doom this one bright spot in an otherwise depressing U.S. diplomatic landscape.

For America and Iran, Trump’s rejection of the nuclear deal ends a short episode of cooperation after decades of missed opportunities for better relations. The Iranians who took risks to participate in the years of diplomacy that led to the JCPOA, especially President Hassan Rouhani and Foreign Minister Javad Zarif, now look naive and are politically exposed.

This author has urged Iran to hold on and stick to its commitments under the deal in anticipation of a “regime change” in Washington that will eventually end the Trump presidency, whether through elections or legal action. However, it will be very hard for Iran to keep observing these limits when Washington cheated first and the American president’s advisers now include open proponents of violent regime change in Iran.

There are many other potential negative consequences from not upholding the deal, from increased oil prices to escalating conflict in the Middle East. Iranian influence, far from falling, is on the rise in Lebanon and possibly Iraq, which held parliamentary elections on May 12. Israel may continue to attack Iranian personnel in Syria, raising the prospect for Iranian retaliation either directly or through proxies.

China, already Iran’s largest trading partner, will be the biggest beneficiary in economic terms. Iran will also likely intensify its security cooperation with Russia. Iran, of course, is not blameless for the collapse of the deal. While strictly complying with its nuclear obligations, Iran has continued to interfere in its neighbors, even a country as tangential to Iranian interests as Yemen. Hardline elements in Iran’s security services soured the atmosphere for the nuclear deal early on by holding on to and seizing more dual nationals on flimsy charges.

However, Congress also undermined the agreement by passing legislation by a veto proof majority that required Europeans and others who normally do not need visas to come to the United States to get American visas if they had visited Iran. This was the first violation of the agreement because it acts as a restraint on otherwise permitted trade, and it came under the Obama administration just as the JCPOA was being implemented.

The Trump administration brought a massive new series of challenges, beginning with its first travel ban, which largely targeted Iranians, and continuing with official comments trying to dissuade foreign companies from trading with and investing in Iran. His constant threats to pull out of the deal acted as a disincentive to investment and contributed to the large devaluation in the Iranian currency. Major deals have been put on hold and Iran has yet to receive a single new airplane from Boeing, which got a special carveout in the agreement to sell Iran badly needed passenger aircraft. That $18 billion sale is now officially dead.

In the weeks leading up to Trump’s decision, Iranian officials were referring to the nuclear deal as a “failed experiment” in diplomacy. Zarif, who was educated in the United States and has worked assiduously to try to end the long estrangement of the two countries, was asked by this author at a recent meeting in New York whether he had given up on engagement with Americans. “I haven’t given up on diplomacy because I believe diplomacy is far superior to other means,” he said. “I never say never.” Right now, however, it is hard to see a constructive path forward.

Barbara Slavin is director of the Future of Iran Initiative at the Atlantic Council in Washington, D.C. The views expressed are her own.