Tehran had been gradually reducing its commitments under the deal since the United States withdrew and reimposed sanctions in 2018. With Washington threatening secondary sanctions against European businesses dealing with Iran, Tehran argued that it could no longer reap the financial benefits laid out in the pact in exchange for curbing its nuclear program.
By initiating the dispute mechanism, the Western European signatories begin a process that could eventually result in a "snapback" of U.N. sanctions, although officials made clear such an outcome is not their current intention.
Instead, they appear to hope that triggering the process could help bring Iran back in line with its commitments under the 2015 deal, which it negotiated with the United States, Britain, France, Germany, Russia and China.
A State Department official said European signatories had taken the "right step" in initiating the dispute resolution mechanism. "We believe further diplomatic and economic pressure is warranted by nations," said the official who declined to be named in line with protocol.
In their statement, the three Western European signatories said they would not be joining the Trump administration's campaign of "maximum pressure" against Iran and reiterated their "regret" at the U.S. decision to withdraw.
"Our goal is clear," said German Foreign Minister Heiko Maas in a statement. "We want to preserve the agreement and reach a diplomatic solution within its framework."
That, however, would depend on the path Tehran chooses to take. In a statement Tuesday, Iran's Foreign Ministry said it would have an "appropriate and serious response" to any "ill-willed or unconstructive actions."
It said that since Iran had begun a dispute process itself a year and a half earlier, after the U.S. withdrawal, it deemed Tuesday's announcement "nothing new."
If European countries continue to follow the United States in a "subordinate way" and "abuse" the agreement, then "they must also prepare to accept the consequences," the Foreign Ministry said.
A State Department spokesperson applauded the European decision, saying, "The time is now to end Iran's extortion."
"Nations must unite behind this effort to hold the Iranian regime accountable for its continued destabilizing actions," the spokesperson said.
President Trump has repeatedly called on European allies to withdraw from the Obama-era deal, which he railed against during his 2016 presidential campaign. However, the deal's other signatories have stood by it, arguing that it is the best way to limit Tehran's nuclear program.
Launching the dispute process is unlikely to satisfy the Trump administration, said Ellie Geranmayeh, an Iran expert at the European Council on Foreign Relations.
Europe remains several steps away from abandoning the deal.
The clock will start on a negotiation period that could last 35 days — or longer if there is a mutually agreed extension. After that, a signatory would have to raise the dispute to the U.N. Security Council. Then, if the Security Council cannot agree on a resolution to the dispute — a stalemate would be likely, given that the permanent members already disagree — sanctions would be reimposed.
The aim is “to try and inject a new political environment around the nuclear deal,” Geranmayeh said.
European diplomats also hope the process might buy them time and possibly relieve some pressure from the United States.
“Based on the outcome of the U.S. elections, everyone will have a better calculus of where they go next,” Geranmayeh said.
However, the Europeans will have to carefully manage the dispute process if they want the deal to survive, she said. Iran may not engage, or it may choose to escalate. And the Trump administration could argue that the United States, as an original signatory, has the ability to raise the dispute to the Security Council.
Alternatively, Washington could try to pressure London to raise it. Britain is more closely aligned with the Trump administration than Germany and France are, and it is vulnerable to pressure as it negotiates a post-Brexit trade deal.
Cracks showed in the European position on Tuesday when British Prime Minister Boris Johnson called for replacing the nuclear deal. In a television interview, he said the White House’s main issue with the deal was that it is “flawed” — but also that it was signed by President Barack Obama.
“If we’re going to get rid of it, let’s replace it, and let’s replace it with the Trump deal,” he told “BBC Breakfast.”
Speaking to Parliament, British Foreign Secretary Dominic Raab took a harder line than others in Europe. He outlined Iran’s step-by-step reduction in its commitments since last May, leaving what he described as a “shell” of an agreement.
“Each of these actions were individually serious,” he said. “Together, they now raise acute concerns about Iran’s nuclear ambitions.”
In July, the International Atomic Energy Agency confirmed that Iran had exceeded the nuclear agreement’s limit of 3.67 percent purity in its enriched-uranium production.
Raab said the first step in the process of putting Iran on notice would be a meeting of all the deal’s signatories within 15 days. Iran’s response would be a “crucial test of its intentions and goodwill,” he said.
Russia has remained vocally committed to the deal and has urged Europe to do more to save it. Konstantin Kosachev, head of the foreign affairs committee in the upper house of the Russian parliament, said Europe should also call on the United States to abide by its commitments under the agreement.
“Given Western logic, it turns out that no matter what happens with the JCPOA, Iran should observe it, and if it fails to honor it, it shall be the only party to blame,” he wrote on Facebook. “This is dubious logic, to put it mildly. The U.S. is apparently using and enjoying this impunity in its little unipolar world it has created.”
Josep Borrell Fontelles, coordinator of the dispute process, said he had received a letter from the foreign ministers of Britain, France and Germany referring Iran under the mechanism while calling for constructive diplomatic dialogue.
“In light of the ongoing dangerous escalations in the Middle East, the preservation of the JCPOA is now more important than ever,” he said.
Isabelle Khurshudyan in Moscow, Kareem Fahim in Istanbul, Quentin Ariès in Brussels and Carol Morello in Washington contributed to this report.