US, Iran hold firstround of 'fragile' talks

US and Iranian negotiators ended the first round of high-stakes talks in Switzerland on Sunday without a breakthrough, as back-channel diplomacy continues amid mounting tensions triggered by renewed US threats, Iranian objections and escalating regional instability linked to Lebanon and the Strait of Hormuz.

The quadrilateral talks, called 'Lake Lucerne Summit' at the Burgenstock resort lasted about 80 minutes, according to Iranian state media. The US and Iranian negotiating teams also held separate private talks with Pakistani and Qatari officials, various US media outlet stated.

CNN quoting its diplomatic sources and officials familiar with the discussions, stated that the negotiations between Washington and Tehran have stalled but were not over, with both sides maintaining indirect communication in an effort to bring delegations back to the table.

An Iranian source in contact with the delegation told international media that while differences remain sharp, "talks are ongoing despite hiccups and demands on both sides," adding that the delegations remain in the Swiss resort complex as mediators work through back-channel channels to sustain the process.

However, a US diplomat told Axios that the talks focused on deconfliction mechanisms in Lebanon and enforcing the ceasefire. The diplomat also said that there was good progress on keeping Strait of Hormuz open.

The 'Lake Lucerne Summit' was attended by the US delegation led by Vice President JD Vance and Iranian delegation comprising Parliament Speaker Bagher Ghalibaf and Foreign Minister Abbas Araghchi, besides Pakistani Prime Minister Shehbaz Sharif and Army Chief Field Marshal Asim Munir and Qatari Prime Minister Sheikh Mohammed bin Abdulrahman Al Thani as mediators.

As Vance called on Tehran sat for talks with Iranian leaders, President Trump threatened to restart strikes on Iran for its support of Hezbollah or if it moved to close the Strait of Hormuz. "Iran must immediately stop their highly paid PROXIES in Lebanon from causing trouble," Trump said on social media on Sunday. "If they don't, we'll hit Iran very hard again, just like we did last week, only harder!!!"

The remarks drew a strong rebuke from Iran's chief negotiator Ghalibaf, who accused Washington of "desperation" and warned that Tehran's armed forces were prepared to respond to any escalation. "They would do better to be careful about their statements," Qalibaf posted on X. "Our armed forces are prepared to respond to them in a different manner. They may keep talking, it is we who act."

Iranian officials also objected to the tone of US statements during the negotiations, though both delegations remained present at the venue as mediation efforts continued behind closed doors. Despite the tensions, sources indicated that a draft framework for limited sanctions relief on Iranian oil exports has been finalised at technical level discussions.

According to Iran's semi-official Fars News Agency, an economy expert on the Iranian delegation said the draft was expected to move towards implementation, focusing on easing restrictions on oil and petroleum derivatives under specific provisions of the emerging understanding.

The same framework reportedly links several broader issues to implementation progress, including ending hostilities in Lebanon, reopening critical maritime routes, limited sanctions exemptions, and discussions around frozen Iranian assets. However, Iranian officials have signalled that full implementation of broader provisions remains contingent on de-escalation in Lebanon.

A central point of contention remains the Strait of Hormuz, after Tehran announced it had moved to restrict access in response to Israeli strikes in Lebanon, a claim disputed by the United States military. Washington has instead pushed for guarantees on maritime security and uninterrupted energy flows through the strategic waterway, which handles a significant share of global oil trade.

Alongside maritime tensions, discussions have also been shaped by the fragile situation in Lebanon, where fighting between Israel and Hezbollah has continued to influence the diplomatic track. US officials have indicated that stabilising Lebanon and securing a ceasefire framework remain key priorities alongside any broader agreement with Iran.

Iranian state media reported that while nuclear issues were not formally discussed in the opening session, Tehran has reiterated that it will not abandon its uranium enrichment rights, even as it denies any intention of developing nuclear weapons.

Speaking at the start of the summit, Vance, leading the American delegation, described the opening phase of the talks as part of a wider effort to reset relations. However, by the end of the first round, officials confirmed that the talks remained fragile, with no agreement on key sticking points and uncertainty over whether direct negotiations would immediately resume or continue through intermediaries.

Iranian state media said the talks had entered a "difficult phase" and recessed after the "publication of an insulting message by the US president", according US Associated Press news agency. The Iranian delegation then met with Qatari mediators and left the negotiating site, it added.

Despite the heated social media exchanges, an official with knowledge of the talks later told the AP on condition of anonymity the Iranian delegation remained engaged in the talks and has not indicated to mediators any intention to leave.

The talks come after an interim agreement was signed last week by President Trump, his Iranian counterpart, Masoud Pazeshkian and Prime Minister Shehbaz Sharif as mediator, triggering a 60-day sprint to reach a final agreement to end hostilities.