Tehran has leveraged its effective control over the waterway – through which around a fifth of the world’s oil and natural gas usually flows – in the war, which began with US and Israeli strikes on 28 February.
It has warned – and in some instances attacked – vessels trying to cross the strait.
The US has a significant military presence across the Gulf, with bases in Qatar, Bahrain, Kuwait, the UAE, Saudi Arabia and Oman.
It was announced on Saturday that the British Royal Navy was sending a warship to the Middle East, where it could join an international mission to safeguard shipping in the Strait of Hormuz.
UK Prime Minister Sir Keir Starmer, who together with French President Emmanuel Macron is championing the mission, has said the shipping mission would only take place once fighting in the region ends.
In response, Iran on Sunday warned of a “decisive and immediate response” to any French or British deployments in the strait.
Macron then said that France had “never envisaged” a naval deployment but rather a security mission that would be “co-ordinated with Iran”.
Iran has also retaliated against Arab allies of the US in the Gulf.
The UK’s Maritime Trade Operations Centre (UKMTO) – which monitors international shipping routes – said a bulk carrier had been “hit by an unknown projectile” about 23 nautical miles (43km) north-east of Doha in Qatar, causing a small fire but no casualties.
Iran’s Fars news agency later cited an unidentified source as saying that vessel had been “sailing under the US flag and belonged to the United States”.
Also on Sunday, Kuwait said drones had entered its airspace and that the military had “dealt with them”.
Hours later, the UAE said its air defences had intercepted two drones coming from Iran.
Defence ministers from more than 40 nations will meet on Monday to discuss UK-led plans to protect shipping in the strait.
John Healey and his French counterpart Catherine Vautrin will co-chair the meeting, where the coalition partners are expected to outline how they might police maritime traffic once hostilities cease.
Trump wrote in a Truth Social post on 6 May that if Iran did not agree to a deal, “the bombing starts, and it will be, sadly, at a much higher level and intensity than it was before”.
