A joint press conference by the European Union’s foreign-policy chief and the U.S. Secretary of State descended into a thinly veiled exchange of rebukes, adding to signs of increased strain in the world’s most powerful alliance.

“The Iran nuclear deal is a key strategic priority for European security but also for regional and global security,” the EU’s Federica Mogherini told reporters on Tuesday, emphasizing that the agreement only dealt with nuclear issues. “Dismantling an agreement on nuclear issues that is working—as the International Energy Agency has certified nine times—would not put us in a better position to discuss all the rest on the country.”

That conflicts with U.S. President Donald Trump’s plan to pull the plug out of the Iran nuclear deal, which has drawn sharp criticism from the EU. The bloc has been lobbying Congress to overrule the president’s decision, saying that scrapping the accord would endanger stability in the wider region.

“Iran is carrying out a number of destabilizing actions in the region and we’ve seen this recently with ballistic missiles being fired from Yemen, which is our belief are sourced from Iran,” U.S. Secretary of State Rex Tillerson said after Mogherini’s comments. Even though the EU says that any such concerns shouldn’t lead to the dismantling of the nuclear accord, Tillerson said that “these issues and activities of Iran cannot be ignored and cannot go unanswered and we intend to continue to take action to ensure Iran understands this.”

Capital of Israel

The quarrel adds to a long list of disputes that have come between the U.S. and the EU—from trade protectionism to environmental policies, and from Trump’s apparent endorsement of far-right groups in Europe to his threat of unilateral military action against North Korea.

The latest episode in the saga is over the possibility that the U.S. might unilaterally recognize Jerusalem as the capital of Israel. “A way must be found, through negotiations, to resolve the status of Jerusalem as the future capital of both states,” Mogherini said in her joint press statement with Tillerson. “We believe that any action that would undermine this effort must absolutely be avoided.”

Germany’s acting foreign minister, Sigmar Gabriel, said unilateral U.S. recognition of Jerusalem as Israel’s capital would inflame Middle East tensions.

“That would be a very dangerous development,” Gabriel told reporters on Tuesday at a meeting of foreign ministers from the North Atlantic Treaty Organization.

After his bilateral meeting with Mogherini, Tillerson was due to meet his EU counterparts, ahead of a meeting of NATO foreign ministers in Brussels. Mogherini and Tillerson didn’t accept questions after the briefing.