BREAKING: US retaliates with missile strikes in Iraq, targeting the Iranian-backed Shia

Per TheHill, U.S. airstrikes are underway against an Iran-backed militia group that hit a military base in Iraq, according to multiple media outlets.

On Wednesday Iranian-backed militia groups in Iraq killed two U.S. troops and one British soldier. Earlier Thursday top Pentagon officials said “all options are on the table” for a response.

MPR news reports the U.S. launched airstrikes Thursday in Iraq, American officials said, 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.

One U.S. official said multiple strikes targeted Kataib Hezbollah weapons facilities inside Iraq. The strikes were a partnered operation with the British, that official said. The officials spoke on condition of anonymity because operations were still going on.

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.

Defense Secretary Mark Esper told reporters at the Pentagon earlier Thursday that President 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.”

At the White House, Trump had also hinted that a U.S. counterpunch could be coming, telling reporters, “We’ll see what the response is.” And Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff, told Pentagon reporters the U.S. knows ”with a high degree of certainty” who launched the attack.

On Capitol Hill earlier in the day, Marine Gen. Frank McKenzie, the top U.S. commander for the Middle East, told senators the deaths of U.S. and coalition troops created a “red line” for the U.S., but said he didn’t think Iran has “a good understanding of where our red line is.”

Asked if any counterattack could include a strike inside Iran, Esper said, “We are focused on the group that we believe perpetrated this in Iraq.”

Two U.S. troops and one British service member were killed and 14 other personnel were wounded when 18 rockets hit the base Wednesday. The U.S. military said the 107 mm Katyusha rockets were fired from a truck launcher that was found by Iraqi security forces near the base after the attack.