Yesterday, two U.S. service members and a British soldier were killed in a rocket attack in Iraq. Today, the U.S. is striking back.

Military Times reports that according to a U.S. Defense Department official,  there were also about a dozen people who were injured in a volley of 18 rockets that hit Iraq’s Camp Taji base.

Britain’s Ministry of Defence on Thursday confirmed the death of Lance Corporal Brodie Gillon, 26, a Reserve with the Scottish and North Irish Yeomanry.

Camp Taji, located just north of Baghdad, has been used as a training base for a number of years. There are as many as 6,000 U.S. troops in Iraq, training and advising Iraqi forces and conducting counterterrorism missions.

Phillip Smyth, a fellow at the Washington Institute tweeted: The likely group involved in the attack may be Kata’ib Hizballah once again. It has functioned as a spear point for IRGC in Iraq. The rockets used are quite popular with Iran’s proxies.

2. The likely group involved in this attack may be Kata'ib Hizballah once again. It has functioned as a spear point for IRGC in Iraq. The rockets used are quite popular with Iran's proxies.

— Phillip Smyth (@PhillipSmyth) March 11, 2020

AP– 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.

Officials said multiple strikes by U.S. manned aircraft hit five locations and mainly targeted Kataib Hezbollah weapons facilities inside Iraq. The officials spoke on condition of anonymity because details about the operations were not yet public.

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 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.”

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.”