The United States and Iran are set to hold technical-level negotiations in Switzerland on Sunday, as US Vice President JD Vance confirmed he will travel to the country “in the coming days” to advance a fragile interim peace agreement. The talks, to be held at the Bürgenstock resort, come as Tehran announced a new closure of the Strait of Hormuz in retaliation for Israeli strikes in Lebanon, throwing the viability of the deal into question.

According to US officials, the negotiations are proceeding despite the renewed tensions. Vance, in an interview with Fox News, said American envoys Jared Kushner and Steve Witkoff were already in Switzerland handling “technical aspects” of the discussions. The US Central Command (CENTCOM) maintained that maritime traffic through the Hormuz Strait had not been interrupted and that dozens of commercial vessels continued to transit, effectively contradicting Iran’s statement. Washington insists that all parties must uphold the agreement signed earlier in the week, which led to the reopening of the waterway and a lifting of US naval restrictions.

Viewed from Tehran, the diplomatic channel remains open but under strain. Iranian state television confirmed a delegation was en route to Bürgenstock, with Foreign Minister Abbas Araghchi reportedly among them. However, foreign ministry spokesperson Esmaeil Baghaei cautioned that the implementation phase would test the agreement’s durability. Iran’s military command directly accused Israel of breaching the terms of the understanding with Washington by continuing air operations in southern Lebanon, and said the strait closure was a “first step” that could be followed by further measures.

Pakistan, which together with Qatar has mediated the process, announced it would facilitate Sunday’s technical meetings as a follow-up to the Islamabad Memorandum of Understanding signed earlier. The talks are intended to resolve outstanding operational details of the interim accord, which provides for a 60-day negotiating period to address Iran’s nuclear programme, sanctions relief, and a proposed $300 billion post-war reconstruction fund. While the deal has allowed Iran to resume unrestricted oil exports and frozen assets to be released, its implementation remains contingent on a durable calm in Lebanon.

Analysts in Europe note that the simultaneous pursuit of negotiations and brinkmanship reflects the high stakes for both sides. The Strait of Hormuz handles roughly 20 percent of global petroleum trade, and any sustained disruption would jolt energy markets. With Vance’s postponed trip now back on track and mediators scheduling subsequent sessions, the diplomatic effort continues in a volatile environment where each side seeks to leverage its position without collapsing the process.