Several major economic powers - dependent on the clear passage in the Strait of Hormuz - have embarked on preventive measures in the event Iran closes the strait and curbs the free flow of this crucial international oil vein.
British Defence Minister Ben Wallace said he had ordered the warships HMS Montrose and HMS Defender to prepare for escort duties for all ships sailing under a British merchant flag in the Strait of Hormuz.
"The government will take all necessary steps to protect our ships and citizens at this time", Wallace said, cited by Reuters.
Wallace said that Washington was entitled to defend itself against a threat, after Iranian military commander Soleimani was assassinated, but urged all parties to exercise restraint.
"We urge all parties to engage to de-escalate the situation. Under international law the United States is entitled to defend itself against those posing an imminent threat to their citizens", Wallace said, cited by Reuters, adding that he had spoken with US Department of Defence Secretary Mark Esper.
Before the long-simmering US-Iran tension - caused by the Trump administration's unilateral withdrawal from the Iran nuclear deal - hit a menacing low on Friday after the US military in an airstrike assassinated the top Iranian general in Baghdad, the Gulf region was already treated as a potential conflict zone.
Last year, a series of attacks on tankers in Gulf waters, and a drone attack against oil facilities in Saudi Arabia, worsened the situation, with the Trump administration and its allies placing the blame on Iran. Tehran has refuted all accusations.
In the wake of a dramatic new turn of the events in the Middle East, unequivocal threats from Iranian leadership vowing "revenge" for the assassinated general and a US full combat preparedness to retaliate, have cast doubt on Rouhani's HOPE initiative to succeed.