Secretary of State Marco Rubio said the US was expecting a response from Iran on a proposal to extend the truce, despite clashes around the Strait of Hormuz, which both sides accused the other of having started.

As a spate of incidents in the Strait of Hormuz test the ceasefire, an Iranian official says, "We are just getting started".

Iran accuses the US of violating the truce, alleging it targeted an oil tanker and carried out attacks on coastal areas.