The US has launched retaliatory air strikes against a pro-Iranian militia group in Iraq, after a rocket attack killed two of its soldiers.

The strikes targeted five weapons storage facilities across the country, the US defence department said.

Two Americans and a British soldier were killed in Wednesday’s rocket attack on the Camp Taji military base.

Earlier, a US commander said an Iranian-backed militia group was likely to have fired the rockets.

“The Iranian proxy group Kataib Hezbollah is the only group known to have previously conducted an indirect fire attack of this scale against US and coalition forces in Iraq,” Central Command chief Gen Kenneth McKenzie told a Senate committee.

The defence department confirmed a series of “defensive precision strikes” had been carried out by manned aircraft against Kataib Hezbollah facilities.

“These include facilities that housed weapons used to target US and coalition troops,” it said. “[The strikes] were defensive, proportional, and in direct response to the threat posed by Iranian-backed Shia militia groups.”

“The United States will not tolerate attacks against our people, our interests, or our allies,” Defence Secretary Mark Esper added. “We will take any action necessary to protect our forces.”

The US has accused Iran-backed militias of 13 similar attacks on Iraqi bases hosting coalition forces in the past year.

The killing of an American civilian in one such incident in December triggered a round of violence which ultimately led Mr Trump to order the assassination of the top Iranian general Qasem Soleimani and Kataib Hezbollah commander Abu Mahdi al-Muhandis the following month.