“US military forces conducted necessary and proportionate strikes on three facilities used by the Iranian-backed Kataib Hezbollah militia group and other Iran-affiliated groups in Iraq,” the US defence secretary, Lloyd Austin, said in a statement.
“These precision strikes are in direct response to a series of escalatory attacks against US and Coalition personnel in Iraq and Syria by Iranian-sponsored militias,” Austin added.
On Saturday, four US personnel suffered traumatic brain injuries after Iraq’s Ain al-Asad airbase was hit by multiple ballistic missiles and rockets fired by militants from inside Iraq.
US troops in Iraq and Syria have been attacked about 150 times by armed groups since the Israel-Gaza war started in October, putting pressure on President Joe Biden to respond militarily, despite political sensitivities in Baghdad.
The attacks against the United States are seen as retaliation for its support of Israel in its war against Hamas in the Gaza Strip which has so far killed more than 25,000, mainly children and women.
The US has 900 troops in Syria and 2,500 in Iraq, advising and assisting local forces to prevent a resurgence of Islamic State, which in 2014 seized large parts of both countries before being defeated.
The war in Gaza has been spreading in recent months, with US forces hitting Houthi targets who have launched attacks on ships in the Red Sea.
On Monday, the US and the UK conducted a further round of strikes against the Houthis in an attempt to stop the rebel group targeting shipping in the southern Red Sea.
That raid marked the eighth time the US had conducted strikes on Houthi targets this months and the second time that the UK had participated.
The Houthis say they are targeting Israel and its western allies in support of Palestinians in Gaza in its targeting of the Red Sea – and there has been no sign that their attacks on shipping slowed after the first wave of attacks.
After Monday’s strikes, a Houthi army spokesperson warned the allied attacks would not go unpunished or unanswered.
