Vice President JD Vance, who has long been sceptical of foreign military interventions and outspoken about the prospect of sending troops into open-ended conflicts, sets off on Friday local time to lead mediated talks with Iran in the Pakistani capital of Islamabad.
It comes as a tenuous, temporary ceasefire appears to be on the precipice of collapsing.
Vance will be joined by Trump's special envoy Steve Witkoff and Trump's son-in-law Jared Kushner, who took part in indirect talks with Iranian negotiators aimed at settling US concerns about Tehran's nuclear and ballistic weapons programs and its support for armed proxy groups in the Middle East before Trump and Israel launched the war against Iran.
The White House has not provided specific expectations for the meeting.
But the arrival of Vance for negotiations marks a rare moment of high-level US government engagement with the Iranian government. Since the Islamic Revolution in 1979, the most direct contact had been when President Barack Obama in September 2013 called newly elected Iranian President Hassan Rouhani to discuss Iran's nuclear program.
Almost immediately after the White House and Iran announced a temporary ceasefire, the sides found themselves at odds over terms of the truce.
Iran insisted that an end to the Israeli war in Lebanon was part of the ceasefire. But Israeli Prime Minister Benjamin Netanyahu and Trump said the truce did not cover Lebanon and the Israeli operations there continued.
The US, meanwhile, demanded that Iran make good on reopening the Strait of Hormuz. The Islamic Republic had closed the critical shipping waterway in response to Israel's intensifying attacks against the Hezbollah militant group in Lebanon.
It's the highest-stakes moment thus far for Vance, who spent much of last year as more of a background player in the Trump White House, while others like Elon Musk and Secretary of State Marco Rubio took turns as ever-present advisers for the president.
Vance, who served in the Iraq War while in the Marines, spent two years as a US senator and a little more than one as vice president, has little diplomatic experience.
Jonathan Schanzer, who is the executive director of the Foundation for Defence of Democracies, a hawkish Washington think tank, said Vance, with little experience on Iran policy, is an interesting choice to lead the delegation.
Trump has noted his vice president was "less enthusiastic" than other top senior officials in the Republican administration, making Vance an intriguing interlocutor for the Iranian side, Schanzer said.
"I think they probably prefer him knowing that his perspective on foreign intervention is one of scepticism," Schanzer said of the Iranians. "I do think that he's going to need some help. I don't think he's ever been engaged in negotiations with this kind of weight, this kind of seriousness. This is as serious as it gets."
Vance and Rubio are seen as the Republican Party's strongest potential 2028 presidential contenders, though neither has given a clear answer about whether he intends to run.
