US Treasury Chief unveils ‘toughest sanctions in history’ against Iran—Tehran threatens to close Strait of Hormuz

US Treasury Secretary Scott Bessent has outlined plans for what he described as the most sweeping sanctions regime ever deployed against Iran, targeting the Islamic Republic’s remaining economic lifelines and warning third-party nations that continued trade with Tehran will carry severe consequences.

Writing in the Financial Times, Bessent signalled that secondary sanctions — measures designed to penalise foreign companies and governments that maintain commercial ties with Iran — will form a central pillar of the strategy, a direct warning to major trading partners including China.

A press conference is scheduled for Monday at 2 p.m. ET, where the Treasury Secretary is expected to detail enforcement mechanisms and timelines as part of the Trump administration’s escalating maximum pressure campaign against the Islamic Republic.

Tehran has responded defiantly. Iranian officials have threatened to halt oil exports through the Strait of Hormuz — the narrow waterway through which roughly a fifth of the world’s oil supply passes — and warned that nations participating in the sanctions framework could face consequences Tehran characterised as tantamount to an act of war.

Global energy markets are watching Monday’s announcement closely, with particular attention on how aggressively Washington intends to enforce measures against Beijing, Iran’s largest remaining oil customer and the partner whose cooperation — or defiance — will ultimately determine the campaign’s effectiveness.