Iran declared on Saturday the closure of the Strait of Hormuz, a choke-point for global oil supplies, accusing the United States and Israel of violating a fragile ceasefire agreement. Hours later, President Donald Trump stated that no tolls would be levied on shipping during a 60-day truce period, but threatened that Washington could unilaterally impose charges if broader negotiations with Tehran fail to reach a final accord. The moves injected immediate uncertainty into crude markets and the nascent diplomatic process, as both sides dispatched negotiators to Switzerland for technical talks scheduled to begin on Sunday.

According to a statement from Iran’s armed forces headquarters, the closure was a direct response to continued Israeli military operations in southern Lebanon and what Tehran described as Washington’s “bad faith” and failure to implement the first clause of a 14-point memorandum of understanding, which calls for a ceasefire on all fronts. Iranian officials warned that unless hostilities ceased and the United States fulfilled its commitments—including the unfreezing of billions of dollars in Iranian assets—the entire framework would be jeopardised. The Iranian delegation, led by Parliamentary Speaker Mohammad Bagher Qalibaf and Foreign Minister Abbas Araghchi, nevertheless travelled to the talks in Bürgenstock, Switzerland, signalling a willingness to test Washington’s seriousness.

In a post on his Truth Social platform, Trump insisted there would be “no tolls” during and after the 60-day period, unless imposed “by and for the United States” should a deal not be completed, framing any future levy as reimbursement for America’s role as “Guardian Angel” to the Middle East. The US Central Command, contradicting Tehran’s closure claim, reported that 55 merchant vessels transited the strait on Saturday carrying more than 17 million barrels of oil, and said it continued to monitor the waterway to ensure free navigation. Vice President JD Vance departed for Switzerland on Saturday evening, joining envoys Jared Kushner and Steve Witkoff, and told reporters he was optimistic about making progress on both a nuclear arrangement and a lasting Lebanon ceasefire.

The brinkmanship cast a shadow over talks mediated by Pakistan and Qatar, which were originally set to begin Friday but were postponed when Iran briefly withdrew over the escalating violence. The ceasefires in Lebanon and Gaza remain tenuous: Israeli strikes killed at least 20 people across Lebanon on Saturday, while Israeli officials accused Hezbollah of launching more than 50 projectiles overnight. Viewed from European capitals, the risk is that the diplomatic track could be overtaken by renewed military escalation, leaving the strategic waterway—through which roughly a fifth of global oil consumption passes—as a pawn in a wider standoff. The first substantive exchanges in Switzerland are expected to focus on the modalities of the truce and the unfreezing of assets, with any movement on larger nuclear questions contingent on the ceasefire holding in practice.