Direct talks between Iran and the United States in Bürgenstock, Switzerland, were thrown into disarray on Sunday after President Donald Trump issued fresh ultimatums, triggering conflicting accounts over whether the Iranian delegation had withdrawn. Iranian state-backed news agencies Tasnim and Fars, both close to the Islamic Revolutionary Guard Corps, reported that the negotiating team left the venue in protest after Trump threatened to attack Iran “with much force” if it did not rein in Hezbollah in Lebanon and warned that blocking the Strait of Hormuz would mean losing “your damn country.” The official IRNA agency said the delegation interrupted the meeting following a separate session with Qatari mediators.

The immediate trigger was a series of statements by Trump across social media and a Fox News interview. He demanded that Iran immediately stop its “well-paid proxies” in Lebanon, otherwise the US would “hit Iran hard again, just like we did last week, but even harder.” He separately threatened to take control of the strait and levy transit fees, and told Iranian leaders that if the waterway were closed they would “not even make it back to your country.” These remarks came as Iranian and US teams convened their first high-level encounter since signing a memorandum of understanding days earlier that had laid out a 60-day window to resolve outstanding disputes, including the nuclear file and the status of Hezbollah’s military activity.

Iran’s chief negotiator, parliamentary speaker Mohammad Bagher Ghalibaf, dismissed the threats as bluster and insisted the armed forces were ready to respond. “We do not believe their threats; they should watch their words,” he wrote, adding that regardless of American rhetoric, “we are the ones who act.” Iranian sources also made the continuation of talks conditional on an end to Israeli operations in Lebanon, a linkage that US officials had hoped to avoid while seeking a sequencing that first addressed the nuclear programme. Viewed from Tehran, the walkout served a dual purpose: it signalled that Washington’s public hardball tactics could unravel the diplomatic track, while reinforcing the domestic narrative that Iran would not negotiate under duress.

Yet Western diplomatic sources offered a sharply different picture. Officials cited by Axios, Bloomberg, and Reuters maintained that the Iranian delegates had not departed and that the talks were paused, not abandoned. One diplomat told Axios that “the Iranian delegation has not left and talks are still ongoing.” A CNN report cited an Iranian source saying conversations were “paralysed but not finished,” with back-channel efforts under way to coax the sides back to the table. The US delegation, led by Vice President JD Vance, had earlier described “major progress,” and Swiss hosts kept the resort available through Monday morning, indicating that a resumption remained technically possible.

Behind the competing narratives lies a fragile process. The memorándum signed the previous Wednesday committed both capitals to a ceasefire and to begin easing sanctions and releasing frozen Iranian assets in exchange for verifiable steps on nuclear non-proliferation. Lebanon has emerged as the deal’s most explosive fault line: Iran insists that a halt to Israeli attacks on Hezbollah must be part of any durable accord, while Washington, according to officials briefed on the talks, views it as an issue for separate security arrangements. For now, the dossier is in a state of suspended animation. No formal date for the next round has been announced, but Qatari and Pakistani mediators are expected to continue shuttle diplomacy to prevent the rupture from becoming permanent.