France, March 21 -- The US statement appeared designed to calm the concerns of energy markets and of Washington's sceptical international allies, more than 20 of whom issued a statement vowing to back efforts to re-open the key sea lane.

Admiral Brad Cooper, head of US Central Command, said US war planes had dropped 5,000-pound bombs on an underground facility on Iran's coast that was storing anti-ship cruise missiles, mobile missile launchers and other equipment.

"We not only took out the facility, but also destroyed intelligence support sites and missile radar relays that were used to monitor ship movements," Cooper said in a video statement.

A statement from the leaders of mainly European countries, including the UK, France, Italy a...