On a Monday afternoon in the Swiss Alps, US Vice President JD Vance stood before reporters at the Bürgenstock resort — the same mountaintop venue that hosted Ukraine peace talks a year earlier — and offered a carefully measured verdict. "We laid a very good foundation for a successful final deal," he said, choosing each word with the precision of a man aware that the architecture beneath those words remained precarious. The talks represented the first formal stage of a two-month negotiating period established under a preliminary understanding reached the previous week. That preliminary deal was itself a consequence of a conflict that began on 28 February, when the United States and Israel launched military operations against Iran.

Iranian Foreign Minister Abbas Araghchi described the outcome on social media as reflecting "major progress," pointing to agreed waivers on Iranian oil and petrochemical exports, the release of some frozen funds, and the outline of a reconstruction plan for Iran. His country's senior negotiators then flew home to Tehran, leaving a technical delegation under Deputy Foreign Minister Kazem Gharibabadi to continue working through the details in Switzerland. Yet the diplomatic process had nearly collapsed before it properly began. On Sunday, President Donald Trump posted a social-media threat to resume military strikes if Iran failed to restrain its allied forces in Lebanon.

Iranian Parliament Speaker Mohammad Bagher Qalibaf responded sharply, warning Washington that Tehran's armed forces were "ready to respond in a different way." The exchange was a reminder that the ceasefire underpinning the negotiations remained contested: Israel continued to conduct strikes in Lebanon even as Iran insisted a halt to that fighting was already part of the interim arrangement.