On Sunday morning, Air Force Two touched down in Switzerland carrying US Vice President JD Vance — and, with him, the most consequential diplomatic gamble of the year. His mission is to translate a framework agreement, signed only last week between Washington and Tehran, into a binding technical deal that would end the ongoing Middle East war. Negotiators on both sides have been given 60 days to do it. That clock is already ticking under considerable pressure.

The pressure intensified almost immediately. Iran's joint military command announced that the Strait of Hormuz — the narrow waterway through which roughly 20 percent of the world's traded oil passes — had been closed again. Tehran cited Israeli military operations in Lebanon and what it described as American "bad faith," accusing Washington of failing to honour commitments made during the framework negotiations. The closure, if sustained, would send energy markets into fresh turbulence and complicate the diplomatic atmosphere in Geneva considerably.

President Donald Trump, speaking before Vance's departure, issued a stark warning of his own: if negotiators could not finalise an agreement, the United States might impose tolls on vessels transiting the Strait of Hormuz.