The U.S. has carried out "necessary and proportionate" strikes in Iraq, Defense Secretary Lloyd Austin said Tuesday.

U.S. forces targeted three facilities used by the Iranian-backed Kataib Hezbollah militia group and other Iran-linked groups, Austin said in a statement. 

The Kataib Hezbollah headquarters was targeted, along with storage, and training locations for rocket, missile, and one-way attack unmanned aerial vehicle capabilities, U.S. Central Command said. 

"These precision strikes are in direct response to a series of escalatory attacks against U.S. and Coalition personnel in Iraq and Syria by Iranian-sponsored militias," said Austin. 

U.S. MILITARY BASES IN IRAQ, SYRIA ATTACKED AGAIN, BRINGING TOTAL TO AT LEAST 90 SINCE OCT. 17

The strikes were in response to the Iran proxy group Kataib Hezbollah's massive ballistic missile attack on al-Asad air base on Saturday, and an attack on al-Asad on Tuesday, a U.S. defense official told Fox News. The group fired 17 ballistic missiles and rockets at the base, where the majority of the 2,500 troops in Iraq are stationed.

On Saturday, the U.S. Army's Patriot missile defense system fired 15 missiles to intercept the ballistic missiles and rockets, but two got through, damaging the base and resulting in four U.S. service members being diagnosed with traumatic brain injury. 

All have returned to duty. 

The attack on al-Asad on Tuesday resulted in only minor injuries. U.S. forces in Iraq have been repeatedly targeted by Iran-linked groups in multiple attacks in recent months. 

"The President and I will not hesitate to take necessary action to defend them and our interests. We do not seek to escalate conflict in the region," Austin said. "We are fully prepared to take further measures to protect our people and our facilities. We call on these groups and their Iranian sponsors to immediately cease these attacks."

U.S. forces have also conducted airstrikes in the region on Yemen's Iran-backed Houthis and have been targeted in Iraq by Iran-linked groups.