Iran hit an oil tanker off the coast of Qatar and Kuwait’s airport on Wednesday while airstrikes battered Tehran. US President Donald Trump has said he could walk away from the war once he felt confident Iran would not be able to build a nuclear weapon, even if Tehran does not agree to a ceasefire.

That raised the possibility the US could withdraw without any guarantee from Iran that it would stop bombing its Gulf Arab neighbours or release its grip on the Strait of Hormuz. Trump said the responsibility for keeping the route open should belong with countries that rely on it.