Negotiations between the United States and Iran aimed at securing a permanent peace agreement faced fresh challenges on Sunday after renewed tensions over Lebanon and a sharp exchange of warnings between Washington and Tehran.

Reports initially suggested that Iran’s delegation had left the Swiss venue hosting the talks following comments by US President Donald Trump, who warned Tehran against supporting Hezbollah activities in Lebanon. However, diplomatic sources later indicated that Iranian negotiators remained engaged in discussions and had not formally withdrawn from the process.

The latest round of negotiations is part of a broader effort to convert the recently signed memorandum of understanding between the two countries into a long-term agreement addressing regional security and Iran’s nuclear programme.

Speaking during the talks, US Vice President JD Vance described the discussions as a “historic meeting” and expressed hope for a lasting improvement in relations. However, differences remain over key issues, including Iran’s regional role, nuclear activities, and the ongoing conflict in Lebanon.

Iranian officials reiterated that Tehran would not abandon its uranium enrichment programme, while maintaining that it has no intention of developing nuclear weapons.

The negotiations come amid continued uncertainty in Lebanon, where clashes between Israeli forces and Hezbollah have repeatedly threatened diplomatic progress. Iran has linked future negotiations to the implementation of commitments aimed at ending hostilities in Lebanon.

Despite the challenges, both sides continue to engage through mediators in an effort to prevent further escalation and advance a broader regional peace framework.