The Royal Navy will accompany ships through the Strait of Hormuz amid heightened tensions between the US and Iran.
Following the US airstrike to kill Gen Qassem Soleimani, one of Iran's top military officers, the Navy will protect UK-flagged ships and has warned against travel in the region.
The move comes several rockets exploded near the US embassy in Baghdad, hours after thousands took to the streets for the funeral ofGen Qassem Soleimanie.
Iran has vowed to take revenge on the US, while President Trump dispatched 3,000 extra troops to Kuwait.
Defence Secretary Ben Wallace said he had instructed the HMS Montrose frigate and the HMS Defender destroyer to return to the key oil passage imminently, adding: “The Government will take all necessary steps to protect our ships and citizens at this time.”
He continued to urge “all parties” to de-escalate the situation, but appeared to give some backing to the US for the first time as he announced the shipping plan.
After speaking to his US counterpart Mark Esper on Friday, Mr Wallace said American forces have been “repeatedly attacked by Iranian-backed militia” in Iraq during “the last few months”.
“General Soleimani has been at the heart of the use of proxies to undermine neighbouring sovereign nations and target Iran’s enemies,” Mr Wallace continued.
“Under international law the United States is entitled to defend itself against those posing an imminent threat to their citizens.”
The practice of escorting ships in the Strait of Hormuz was stood down in November, after being used during the fall-out from the seizure of the British-flagged Stena Impero tanker by Iran in July.
The difference this time, the Ministry of Defence was keen to stress, is UK ships now have a choice to navigate the waters without an escort at their own risk.