Ask PolitiFact: What was the Iran nuclear deal and why did Trump drop out?

President Donald Trump has repeated his push for a nuclear deal with Iran in recent days, seven years after he walked away from a multilateral deal that allowed the U.S. government to monitor Iran’s weapons program.

Trump has vowed to stop Iran from obtaining a nuclear weapon since announcing his candidacy in June 2015. During his first term, Trump withdrew the U.S. from the deal signed by his predecessor, President Barack Obama, and then broke his 2016 campaign promise to negotiate a new one.

As Trump considers the role of the U.S. in Israel’s efforts to take out Iran’s nuclear capabilities, our readers sent us questions about the federal government’s past efforts to stop Iran from obtaining a nuclear weapon.

Some on the left are blaming Trump’s 2018 exit for Iran’s nuclear capabilities. 

"Now the world is reaping the whirlwind of his historic mistake," said Sen. Edward Markey, D-Mass. 

It’s difficult to know exactly what Iran, the U.S. and other countries would have done if the agreement remained in place.

"I don’t know what would have happened if he hadn’t withdrawn the U.S. from the deal," Lisa Koch, an expert on American foreign policy and nuclear weapons and a Claremont McKenna College associate professor of government, told PolitiFact. "But I can say that if the United States had stayed in the (Iran agreement), and if everything had continued to go as it had been going between January 2016 and the U.S. withdrawal, Iran would still have an internationally monitored nuclear program and would not possess uranium enriched to the level at which Iran could decide to build nuclear bombs on a short timeline." 

What was the Iran nuclear deal?

Obama campaigned on a promise to make sure that Iran did not obtain a nuclear weapon. His administration secured an agreement, formally known as the Joint Comprehensive Plan of Action, or JCPOA, that was signed in 2015 by the United States and Iran as well as China, Russia, France, Germany and the United Kingdom.

Under the deal, Iran agreed not to pursue nuclear weapons and to allow continuous monitoring of its compliance in exchange for relief from economic sanctions. Different parts of the agreement were scheduled to last between 10 and 25 years. Obama officials hoped for future renegotiations.

Iran agreed to relinquish nearly all of its enriched uranium stockpile (97%) and 70% of its centrifuges, which are used to enrich uranium. It also agreed to stop plutonium production and to dismantle its plutonium reactor.

Some Democrats joined Republicans in opposition, but they did not have enough votes to block the deal. Critics said it didn’t address other actions by Iran, including support for terrorism, and that it posed a threat to Israel.

We reported in 2017 that Iran had largely complied with the deal, and many experts praised the pact for keeping nuclear weapons out of the hands of Tehran. Over the 28 months the deal was in effect, the International Atomic Energy Agency said it found Iran committed no violations, aside from some minor infractions that were addressed. 

Why did Trump drop out of the Iran nuclear deal?

In May 2018, Trump announced he was pulling the U.S. out of the deal.

"This was a horrible one-sided deal that should have never, ever been made," Trump said. "It didn't bring calm, it didn't bring peace, and it never will."

Trump said he believed the deal should have allowed international weapons inspectors to have greater access to Iranian military sites and that it should have covered Iran’s missile program.

What happened after Trump dropped out?

After dropping out of the compact, the U.S. put economic sanctions on Iran over its nuclear program. Iran reduced its compliance with the deal and stopped complying with international inspectors.

"This expanded Iranian enrichment activities, bringing it closer to the capability to produce a bomb, while reducing the visibility of those activities and making them harder to monitor," said Brendan Green, an expert on nuclear strategy and associate professor at the University of Cincinnati.

Trump and officials in his administration said they wanted a new deal, but that never happened. 

President Joe Biden, who advocated for the agreement as Obama’s vice president, called for a "longer and stronger" agreement if Iran returned to compliance. That never happened, either.

What would have happened if Trump hadn’t withdrawn?

We can’t know with certainty what would have happened had Trump remained in the agreement. 

As a non-proliferation tool, the Obama deal’s key challenge was that many of the key restrictions on Iran would have started expiring in 2025. "If no changes were made to the deal, Iran was going to be in a position to do all of the things that would bring it right up to the threshold of getting a nuclear weapon, and to do so legally," Green said.

Matthew Kroenig, a Georgetown University government professor who was an Iran deal critic, rejected the accusation that Trump is to blame for the current situation with Iran. Kroenig worked under Republican and Democrat administrations, including Obama and Trump’s first term. 

"I think Iran is to blame, they are the ones that have had an illegal nuclear program for 20 years," Kroenig said. "This is the most hopeful moment for dealing with that challenge in the last 20 years." 

Kroenig said the U.S. is in a better place now than it would have been if it was operating under an agreement that was going to expire. "The program may be gone by the end of the week," he said.

Matthew Bunn, a Harvard University nuclear arms control expert, said pulling out of the agreement means that "Iran is much closer to the bomb than it ever has been before. Today, Iran can produce enough material for several bombs in a matter of weeks — then it would have been a matter of months."

Now the U.S. has "very few options available to stop them other than war. We missed the chance to do it diplomatically because of the false hope we could get a better deal by forcing them to capitulate," Bunn said. (When Obama officials were working on the deal, they would sometimes speak with Bunn, he told PolitiFact.) 

More experts said adherence to the agreement as written — with Iran’s compliance and the U.S. staying in — would have slowed down Iran’s nuclear capabilities. 

"We would have bought ourselves several years more of a contained nuclear program and transparency into it, the space to negotiate something longer/stronger (as Biden proposed in 2020 and ostensibly in line with even Trump's goals), and would be no worse today than we were several years ago," said Richard Nephew, senior research scholar at Columbia University who worked at the State Department under Biden. "But, critics said that if we're gonna have a crisis, we might as well have one early. They got their wish."

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