BRUSSELS — In Vienna on Tuesday, the signers of the 2015 Iran nuclear deal will come together with what would appear to be a simple task. They want to restore compliance with an agreement that put strict controls on Iran’s nuclear enrichment, to ensure that it cannot build a nuclear weapon, in return for the lifting of punishing economic sanctions.
Both Iran and the United States insist that they want to return to the deal, known as the Joint Comprehensive Plan of Action, or J.C.P.O.A. But nothing about the meeting will be simple.
President Donald J. Trump pulled the United States out of the accord in May 2018, calling it “the worst deal ever negotiated,’’ and restored and then enhanced harsh economic sanctions against Iran, trying to force it to renegotiate.
Iran responded in part by enriching uranium significantly beyond the limits in the agreement, building more advanced centrifuges, and acting more aggressively in support of allies in the Middle East, like Hezbollah, Hamas, Shia militias in Iraq and the Syrian government of Bashar al-Assad.
intended to create a road map for a synchronized return of both Iran and the United States to compliance with the 2015 deal. It has been at risk of collapse since Mr. Trump repudiated American participation.
The accord was the outcome of years of negotiations with Iran. Under the chairmanship of the European Union, Britain, France and Germany made the first overtures to Iran, joined by the other permanent members of the United Nations Security Council: Russia, China and the United States.
But it was not until the United States started secret talks with Iran under President Barack Obama and agreed that Iran could enrich uranium, though under safeguards, that a breakthrough occurred. Even then, the deal was widely criticized as too weak by many in Congress and by Israel, which saw Iran’s possible reach for a nuclear weapon — an aspiration always denied by Iran — as an existential threat.
The Europeans tried to keep the deal alive, but proved unable to provide Iran the economic benefits it was due after Mr. Trump restored American sanctions that had been lifted under the deal’s terms. The American sanctions, based on the global power of the dollar and the American banking system, kept European and other companies from doing business with Iran, and Mr. Trump intensified the pressure by adding many more sanctions.
agreed in late February to keep recording information on its inspection equipment for three months, but without granting I.A.E.A. access. If economic sanctions are not lifted in that time, Iran says, the information will be deleted, which would leave the world in the dark about key parts of the nuclear program.
Iran insists it can return to compliance with the deal quickly, but wants the United States to do so first. The Biden administration says it wants Iran to go first.