ieExplains: Why is the US threatening to block Iranian ports and how would it work?

Threat has left markets in another period of uncertainty, with questions over how the blockade will be enforced

A cargo ship sails in the Arabian Gulf towards Strait of Hormuz in United Arab Emirates, Sunday, March 15, 2026. (AP Photo/Altaf Qadri)

Donald Trump has said the US will begin a blockade of the strait of Hormuz, after ceasefire talks with Iran ended without an agreement over the weekend.

The strait has emerged as Iran’s most effective weapon in its asymmetric war with the US. Since 28 February, the US and Israel have pounded Iran, striking thousands of targets and killing dozens of the country’s most senior leaders.