The US conducted a new round of airstrikes early on Tuesday in Iraq, most likely killing militants and destroying three facilities used by Iranian proxies that had been targeting American and coalition troops, US officials said.

The US strikes were in retaliation for a series of assaults, including a drone attack hours earlier by members of Kataib Hezbollah and affiliated groups on Erbil air base in Iraq, according to Adrienne Watson, a National Security Council spokesperson. The drone attack injured three American service members, one of them critically, she said.

“My prayers are with the brave Americans who were injured,” defence secretary Lloyd Austin said in a statement.

The latest strikes targeted facilities used by Kataib Hezbollah, a militia group in Iraq that is considered a proxy of Iran. The US blames Iran and the militias aligned with it for what has become a near-daily barrage of rocket and drone attacks against US forces in Iraq and Syria.

The Biden administration has sought to calibrate retaliatory airstrikes to ultimately deter such groups while avoiding a wider war.

After President Joe Biden was informed of the Erbil attack on Christmas morning, he ordered the defence department to prepare response options, White House officials said. Later in the day, he authorised strikes that were conducted at about 8:45pm Eastern time.

Biden chose Kataib Hezbollah and affiliated facilities that had been used to launch unmanned aerial drone attacks, officials said.

Last month, the US struck an operations center and a command-and-control node south of Baghdad used by Kataib Hezbollah. The group’s political wing is part of the coalition of Iraqi Prime Minister Mohammed Shia al-Sudani.

Since the October 7 Hamas attacks on Israel, Iran-backed groups in Iraq, Syria and Yemen have launched a slew of attacks on US troops and bases and on commercial ships transiting the Red Sea.

The Biden administration has retaliated against the militants in Iraq and Syria but has so far avoided hitting the Houthi militants in Yemen.

New York Times News Service, Reuters