As US and Iranian delegations sat down for direct talks at the Bürgenstock resort in Switzerland on Sunday, President Donald Trump issued a stark warning on his Truth Social platform, threatening to strike Iran 'very hard again — just like we did last week, only harder' if Tehran did not immediately curb its 'highly paid proxies' in Lebanon. The post, which did not name Hezbollah explicitly but referenced forces 'paid' by Iran, landed hours after the US vice-president, JD Vance, praised 'great progress' toward preserving the fragile Lebanon ceasefire. The talks, attended by mediators Qatar and Pakistan, were convened under a 14-point memorandum of understanding signed days earlier that mandates a cessation of hostilities on all fronts, including Lebanon.

Viewed from Washington, the threat is part of a broader pressure campaign. Trump told reporters earlier that the MoU was 'not final' and that bombing could resume if Tehran 'doesn't behave.' In a separate conversation with Fox News, the president said he had warned Iranian officials overnight that closing the Strait of Hormuz would mean they ‘won’t have a country,’ adding the US might 'take over' the waterway and impose transit fees if no deal is reached within 60 days. American officials argue that Hezbollah’s continued action, and by extension Iran’s, threatens the diplomatic process. Meanwhile, congressional Democrats have urged Secretary of State Marco Rubio to brief lawmakers on the agreement, signalling unease over the administration’s strategy.

From Tehran’s perspective, the US ultimatum disregards what it sees as Israeli violations of the same ceasefire. Iranian state-affiliated media stress that the MoU explicitly requires an end to fighting on all fronts, particularly Lebanon, yet Israel launched airstrikes that killed at least 30 people in southern and eastern Lebanon on Saturday. Iran’s joint military command declared the Strait of Hormuz was effectively closed to vessels, citing Israeli breaches. Analysts in the region note that for Iran, Hezbollah is a strategic ally, not a proxy to be ordered about; they view Trump’s language as an attempt to impose a one-sided interpretation of the ceasefire, while the US has been unable or unwilling to restrain Israel.

The exchange of threats underscores the fragility of a peace process that had already been buffeted by renewed clashes. The war began on 28 February with a US-Israeli offensive against Iran, triggering retaliatory strikes and a de facto blockade of the Strait of Hormuz, which handles roughly one-fifth of global oil shipments. Although an earlier round of talks in Islamabad collapsed in April, a lull held until last week’s direct exchanges. The new 60-day negotiating window is meant to address nuclear issues, the strait’s status, and a permanent ceasefire, but the gap between Washington’s demands and Tehran’s red lines remains wide. With both sides warning of harder blows, the Brussels-style talks face immediate headwinds, and no date has been set for a follow-on meeting.