In this Monday, March 2, 2020 file photo, U.S. Defense Secretary Mark Esper, left, speaks during a briefing with the Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley, at the Pentagon in Washington.

In this Monday, March 2, 2020 file photo, U.S. Defense Secretary Mark Esper, left, speaks during a briefing with the Chairman of the Joint Chiefs of Staff Army Gen. Mark Milley, at the Pentagon in Washington. AP Photo

US-Led Airstrikes Underway in Iraq; Retaliation Against Iran-Backed Group That Killed Americans

The operation against Kata’ib Hezbollah is targeting weapons storage facilities.

This story has been updated.

The United States carried out airstrikes in five locations across Iraq against the Iran-backed militia group that killed two Americans and one U.K. medic on Wednesday, according to multiple U.S. officials and confirmed by the Pentagon Thursday night. 

The operation targeted weapons storage facilities that “housed weapons used to target U.S. and coalition troops,” according to a Defense Department statement. 

“These strikes were defensive, proportional, and in direct response to the threat posed by Iranian-backed Shia militia groups who continue to attack bases hosting coalition forces,” the department said. “These terror groups must cease their attacks on U.S. and coalition forces or face consequences at a time and place of our choosing.”

Gen. Frank McKenzie, commander of U.S. Central Command, hinted in testimony earlier Thursday that Wednesday’s attack was conducted by Kata’ib Hezbollah, the same Shia militia group that attacked another Iraqi military base in December, killing an American contractor. 

“The Iranian proxy group Kata’ib Hezbollah is the only group known to have previously conducted an indirect fire attack of this scale against U.S. and coalition forces in Iraq,” McKenzie said.

Related: Iranian Proxies Killed Americans In Iraq, Pentagon Leaders Say

The December attack led President Donald Trump to order the January killing of Iranian Gen. Qassem Soleimani in Iraq, increasing tensions between Washington and Tehran. 

Outside analysts were closely watching whether any retaliation for Wednesday’s attack at Taji air base would be limited to proxy targets inside Iraq — or whether Trump would move to strike targets inside Iran in a dramatic escalation of simmering tensions between the two nations. Trump has signalled that the death of an American is his “red line” for military action, and senior administration officials, including Secretary of State Mike Pompeo, have said that the U.S. will hold Iran responsible for the acts of its proxies. 

But the latest strikes were limited to militia targets within Iraq, and the Pentagon in its statement sought to emphasize that they were “defensive.” 

The airstrikes come less than 24 hours after the House passed a resolution that seeks to limit Trump’s ability to wage war on Iran without Congress’s approval. That binding resolution now awaits Trump’s signature or veto.

Defense Secretary Mark Esper and Joint Chiefs Chairman Gen. Mark Milley earlier on Thursday vowed to hold accountable those behind Wednesday’s attack, a barrage of 18 Katyusha rockets.

“We’re going to take this one step at a time, but we have to hold the perpetrators accountable. You don’t get to shoot at our bases and kill and wound Americans and get away with it,” Esper said. We’ve been very clear about this.” 

Lawmakers have questioned whether the Trump administration’s Iran strategy has been successful in constraining Iranian-backed attacks on U.S. interests in the region. Following the killing of Soleimani, Iran responded with a missile attack on another Iraqi air base, al-Asad, leaving 110 U.S. soldiers with traumatic brain injuries. The administration declined to respond, and Pentagon officials and Republican lawmakers have boasted that the January killing had “reset deterrence” in the region, after months of rocket attacks from Iranian proxies and ship seizures in the Gulf.

But the Taji attack “challenged the notion” that Iran has been cowed, the top Democrat on the Senate Armed Services Committee, Sen. Jack Reed, D-R.I., told McKenzie during his appearance before the committee earlier in the day. 

“I believe we have reestablished a rough form of deterrence, what I would call contested deterrence with Iran at the level of state-on-state attacks,” McKenzie said. “By that I am referring to obviously attributable ballistic missile attacks from Iran launched on U.S. forces. I don’t think that’s an imminent threat.

“What has not been changed is their continuing desire to operate through their proxies indirectly against us. And that is a far more difficult thing to deter,” he said.