As fragile U.S. talks with Iran got under way last weekend in Switzerland, President Trump tossed an unexpected grenade—a social-media threat to attack Iran if it didn’t stop funding its allied Lebanese militia Hezbollah.
Mohammad Bagher Ghalibaf, the chief Iranian negotiator, was unaware, having left his phone outside the negotiating room. When an aide briefed Ghalibaf on the president’s comment, he turned to chide his U.S. counterpart, JD Vance, people familiar with the matter said.
Ghalibaf calmly told the vice president the threats were a breach of the opening paragraph of the memorandum of understanding Trump had signed just days earlier committing the U.S. and Iran not to attack or threaten each other. Then his team ended the face-to-face talks.
“I told Vance, ‘Today your president has issued threats. Understand that we never negotiate under threats or pressure,’” he said in an interview with Iranian state television Tuesday. “The American side sought another meeting through the mediators, but we refused.”
The people familiar with the matter gave a similar account of the confrontation.
Inside the room, Vance told the Iranians that Trump meant that if Tehran violated the deal, the U.S. would respond, said a U.S. official familiar with the negotiations. Vance pushed for a break in the talks to allow the Iranians time to consider the proposals, not because of Trump’s post, the official said. Later, he defended Trump, saying he was responding to Iranian “trash talk” in order “to correct the record” without elaborating.
It wasn’t the first time Trump’s social-media outbursts had become a disruptive wild card in the talks. Mediators repeatedly warned the U.S. during the long negotiations that the posts were threatening efforts to close a deal. They tried to get Iran to ignore what he says in public and focus on what his negotiators said in private.
The effort underscores the new reality Trump has created for diplomacy with his unrestrained, highly public style and reliance on nontraditional envoys in place of seasoned diplomats.
The back and forth involves a lot of theater. After issuing a profanity-laced warning to Iran in April to open the Strait of Hormuz, adding “Praise be to Allah,” Trump told an aide he wanted to look as unstable as possible to prod Iran to the negotiating table. He later threatened to destroy Iran’s export terminal at Kharg Island, its power plants and its civilization.
After Iran said it was ending the weekend talks, Ghalibaf and his delegation strolled from the luxurious negotiations venue to the tiny hotel where they were staying. Talks continued indirectly through Pakistani and Qatari mediators, the people familiar with the matter said.
Still, Iranian diplomats say the president’s unusual style has them reading “The Art of the Deal,” the 1987 book written by Trump and journalist Tony Schwartz where the future president outlines his negotiating tactics as a real-estate tycoon. The bestseller advises negotiators to use extreme, unpredictable demands to create anxiety and force concessions from rivals.
Iranian negotiators have told mediators that they consulted a team of psychologists to help them understand the president’s mindset, some mediators said. Iranian diplomats work with the specialists to try to predict Trump’s public response to Iran’s proposals, they said.
A person familiar with Iran’s diplomacy in Switzerland said its negotiating team there doesn’t include psychologists and the country prefers not to engage in psychological speculation on Trump’s motives or decisions.
Political analysts and mediators say the president’s loud protestations have yet to yield extra concessions from the Iranian side.
“Trump is applying the lessons of ‘The Art of the Deal,’ making extreme threats to test the other side’s resolve,” said Mohamed Amersi, an Iran expert and member of the Global Advisory Council of the Wilson Center, a Washington think tank. “But the Iranians…are well aware of his tactics. It won’t change the dynamics.”
After restarting the weekend talks by working through mediators, Tehran successfully blocked U.S. attempts to insert a mention of the International Atomic Energy Agency—which monitors Iran’s nuclear program—into the final communiqué and wrapped up agreement on the U.S. commitment to allow Iranian oil sales in dollars, the people familiar with the matter said. Another person familiar with the U.S. position said Tehran didn’t block the American attempt to include the IAEA. That agency’s work was always meant to be dealt with separately, this person said.
Still, Iranian officials and mediators have said Trump’s social-media posts have made it harder for more pragmatic officials in Tehran to convince hard-liners the U.S. could be trusted to deliver on its commitments.
In early April, Trump threatened to bomb Iran’s power stations and, later, to destroy the country. “A whole civilization will die tonight,” he warned on April 7.
At the time, the U.S. was seeking a 45-day ceasefire, an extended period Iran feared would be used by Washington and Israel to boost their forces. Iran decided to ignore Trump’s threat—seeing it as a negotiating tactic—and got what it wanted, a 15-day truce instead, Iranian officials and mediators said. A U.S. person familiar with matter said that Trump was serious about his message and said the Truth post led to communications with Iran.
Ten days later, another Trump post helped drive a wedge between Iranian moderates and hard-liners. Minutes after Iranian Foreign Minister Abbas Araghchi declared the Strait of Hormuz completely open following a truce in Lebanon, Trump responded on social media that the U.S.’s own blockade would remain in force.
Iran’s security forces, which opposed any concession to the U.S., seized on the president’s posting, later saying the strait remained shut.
Write to Benoit Faucon at benoit.faucon@wsj.com, Summer Said at summer.said@wsj.com and Natalie Andrews at natalie.andrews@wsj.com
