US Treasury Secretary Scott Bessent has warned Iran of "the single greatest financial offensive ever", describing it as an "economic D-Day" that would sever all economic ties with Tehran and isolate any nation continuing financial dealings with it. The warning comes as Bessent claimed the US-Israel war with Iran was "entering its endgame", though it follows a pattern of threats and subsequent climbdowns from the Trump administration during the conflict. Iran dismissed the comments and threatened to halt all regional oil exports if the war continues, while also warning shipping against passing through the Strait of Hormuz without its permission.

Bessent set out his stance in a Financial Times opinion piece but gave no specifics, with further detail expected at a press conference on Monday at 13:00 local time (18:00 BST). The Strait of Hormuz normally carries a fifth of the world's oil and gas but has been effectively blocked by Iran since the conflict began in late February, contributing to higher petrol and diesel prices and rising cost-of-living concerns, with US petrol prices above $4 a gallon ahead of November's mid-terms. Iran already faces heavy US sanctions after Trump withdrew from the 2015 nuclear deal in 2018, and the latest threat follows an April wave of sanctions on foreign banks and firms trading with Tehran.