BRUSSELS — European leaders said Friday that President Trump’s expected decision to strip backing from the nuclear deal with Iran could undermine further international attempts to restrict Tehran’s ability to expand its atomic program.
At the same time, Europe readied measures to keep the deal on track despite the U.S. uncertainty.
European diplomats have started a wide-ranging effort to lobby U.S. lawmakers in recent weeks on the assumption that Congress will be the main battleground over the future of U.S. participation in the two-year-old deal between Iran and six world powers. The pact limits Iran’s uranium enrichment in exchange for lifting international sanctions.
But even if lawmakers ultimately choose to preserve the agreement, Europeans warned that U.S. credibility had already been dealt a significant blow. That could harm attempts to address both Iran and North Korea, which has threatened to strike the United States with nuclear weapons.
“Keeping faith to an agreement is absolutely fundamental in international diplomacy. And this is exactly what the president is putting into question,” said Norbert Roettgen, the chairman of the foreign affairs committee of the German parliament and a top ally of German Chancellor Angela Merkel. Germany is one of the parties to the deal.
Not backing the agreement, he said, “would have a disastrous consequence with regard to the Middle East. Perhaps a nuclear race would be ignited. It would drive a real wedge into international relations between the U.S. and Europe. And it would make North Korea even more complicated because the credibility of the United States would suffer.”
Europe — long Washington’s most important partner in global security and diplomacy — was already reeling from Trump’s decision to pull out from the Paris Climate accord, another ambitious international agreement negotiated by the Obama-era White House.
But many European leaders view any damage to the Iran deal as far graver for global security, since it could exacerbate nuclear crises in both the Middle East and the Korean Peninsula.
The nuclear agreement, signed in 2015, was the result of years of painstaking negotiations and President Obama and considered a highlight of his diplomatic legacy.
But skeptics in Congress imposed a requirement that the U.S. president recertify every 90 days that Iran is in compliance and that the deal remains in Washington’s national security interest. Trump has already recertified the deal twice, but he has said it was terrible for the United States, viewing it as a legacy of weak bargaining by Obama.
European diplomats said that they shared U.S. concerns about Iran’s ballistic missile program and its aggressive behavior in its region, and that they welcomed negotiations that would change Tehran’s course.
They said that Trump’s expected decertification of the deal would harm efforts to address those additional issues, not help them, by damaging trust that the White House would hold to any international agreement.
“This is a real problem in terms of giving the cushion that Europeans need to actually collaborate as partners with the United States on other aspects of Iranian behavior that they in Europe also find problematic,” said Ellie Geranmayeh, an Iran expert at the European Council on Foreign Relations, summing up views from several European countries.
The International Atomic Energy Agency, which is charged with inspecting Iran’s nuclear program on the ground, has said that Iran is fully in compliance. Iran has centrifuges that can produce enriched uranium for power and research reactors, but has not pushed the program to levels to make weapons-grade material. Iran has repeated insisted it does not seek nuclear arms.
The agreement “takes away the risk of a nuclear arms race in the region,” said a senior E.U. official, briefing journalists in Brussels under ground rules of anonymity. “All the other issues of concern that may come up will not be better served if we take away the agreement.”
European leaders have said it would be impossible to renegotiate the agreement, which took 12 years to reach.
If the deal falls apart, that would merely strengthen Iran’s position on the world stage, French President Emmanuel Macron said last month in an interview with a group of reporters in New York.
“What’s the scenario? We will put ourselves in the North Korea situation … and discover in X number of years that they have a nuclear weapon,” Macron said.
He said he wanted to broker additional restrictions on Iran’s behavior, but without abandoning the nuclear accord.
Discussions have already started in European capitals about how to protect E.U. companies against any U.S. effort to reimpose sanctions on Tehran.
Europe is concerned not only that its own industries could be exposed but also that Iran could abandon the agreement if it no longer feels economic benefits from the deal, diplomats said.
European policymakers said they hoped that Iran and the other parties to the agreement would hold to it, even in the event of a U.S. pullout. But they acknowledged that Iran made the nuclear concessions primarily because of the promise of U.S. sanctions relief, and that Europe played a smaller role.
One measure to improve the economic climate would be measures to extend government-backed financing to European businesses investing in Iran, said Helga Schmid, the secretary general of the European Commission’s diplomatic arm, the European External Action Service, at a conference earlier this month.
That would undo some of the brakes on European business deals with Tehran — but it could also put the E.U. in direct contravention of any possible new U.S. sanctions. Europeans leaders are also searching for legal methods to protect their businesses from the reach of possible U.S. sanctions.
But some policymakers say that their concerns about Trump’s likely decision extend all the way to the future of global stability. Their concern is that it may push North Korea down the path to war by damaging any faith that Pyongyang might have about the value of nuclear negotiations.
“If you conclude an agreement with a country that wants to be a nuclear power or one that has a nuclear program, the international community has to give it a measure of respect,” a senior European diplomat said, speaking on condition of anonymity to discuss sensitive negotiations.
“We want Pyongyang to return to the negotiating table,” the diplomat said.
Almut Möller, head of the Berlin office of the European Council on Foreign Relations, said Trump’s move on Iran was yet another decision that laid bare the depth of the disconnect between European capitals and the American administration.
Trump may want to end U.S. participation in an agreement he has long disparaged, but in Berlin she said the deal is “seen as a masterpiece of European diplomacy.”
But even if the deal survives, she said, trans-Atlantic relations have already been dealt a formidable blow.
“The major concern is that the rules-based order that the U.S. had a hugely formative role in shaping is now being undermined by the U.S.,” she said.
Witte reported from Berlin. Erin Cunningham in Istanbul and James McAuley in Paris contributed to this report.