MORE NEWS: U.S. LAUNCHES AIRSTRIKES IN IRAQ TARGETING IRAN-BACKED SHIA MILITIA MEMBERS,

WASHINGTON — The U.S. launched airstrikes Thursday in Iraq, targeting the Iranian-backed Shia militia members believed responsible for the rocket attack that killed and wounded American and British troops at a base north of Baghdad, the Pentagon said.

U.S. officials said multiple strikes by U.S. fighter jets hit five locations and mainly targeted Kataib Hezbollah weapons facilities inside Iraq. A Defense Department statement said the strikes targeted five weapons storage facilities “to significantly degrade their ability to conduct future attacks.”

The strikes marked a rapid escalation in tensions with Tehran and its proxy groups in Iraq, just two months after Iran carried out a massive ballistic missile attack against American troops at a base in Iraq. They came just hours after top U.S. defense leaders threatened retaliation for the Wednesday rocket attack, making clear that they knew who did it and that the attackers would be held accountable.

“The United States will not tolerate attacks against our people, our interests, or our allies,” Defense Secretary Mark Esper said. “As we have demonstrated in recent months, we will take any action necessary to protect our forces in Iraq and the region.”

The Pentagon statement said the facilities hit in the precision strikes were used to store weapons used to target the U.S. and coalition forces. It called the counterattack “defensive, proportional and in direct response to the threat” posed by the Iranian-backed Shia militia groups.

U.S. officials said the locations of the strikes were largely around the Baghdad region. One U.S. official said there were two strikes at Jurf al-Sakher, one in Karbala, one at Al-Musayib, and one at Arab Nawar Ahmad. The official said the U.S. expected casualties would be lower than 50, and said the main effort was to hit the weapons.

An official with the paramilitary Popular Mobilization Units told The Associated Press that two Iraqi federal police personnel were killed in Jurf al-Sakher.

Esper told reporters at the Pentagon earlier Thursday that President Donald Trump had given him the authority to take whatever action he deemed necessary.

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