The US military on Thursday struck a site in Syria used by two Iranian-backed militia groups in response to rocket attacks on American forces in the region in the past two weeks.

“Up to a handful” of militants were killed in the strikes, a US official told CNN.

The strikes, which mark the US military’s first known action under President Joe Biden, swiftly drew criticism from a Democratic lawmaker. The site was not specifically tied to the rocket attacks but Secretary of Defense Lloyd Austin said he was “confident” it was used by the same Iranian-backed Shia militias that had fired rockets at US and coalition forces.

Pentagon spokesman John Kirby said the strikes took place “at President Biden’s direction” and were authorized not just to respond to the recent attacks against American and coalition forces but also to deal with “ongoing threats to those personnel.”

“Specifically, the strikes destroyed multiple facilities located at a border control point used by a number of Iranian-backed militant groups, including Kata’ib Hezbollah and Kata’ib Sayyid al Shuhada,” Kirby said.

“The operation sends an unambiguous message; President Biden will act to protect American coalition personnel. At the same time, we have acted in a deliberate manner that aims to de-escalate the overall situation in both Eastern Syria and Iraq.”

The site the US struck on Thursday is believed to be used as part of a weapons smuggling operation by the militias, according to a US official. The strikes were conducted to degrade the groups’ ability to carry out attacks and to send a message about the recent attacks, the official said.

Decision made from the ‘top down’

The decision to target the site in Syria was made from the “top down,” a defense official said. Austin told reporters that Biden had authorized the strike on Thursday morning, after he had recommended the President take action.

“We’re confident in the target we went after,” Austin said on a flight back to Washington from San Diego on Thursday. “We know what we hit. We allowed and encouraged the Iraqis to investigate and develop intelligence, and that was very helpful to us in refining the target.”

Kirby said Biden authorized the strikes after consulting with US allies, including coalition partners, and that they had taken place at about 6 p.m. ET.

A US strike against Kata’ib Hezbollah in Iraq on December 29 triggered complaints from the Iraqi government about violations of its sovereignty. Days later, members of the group and other Iran-backed militias marched on the US Embassy in Iraq, damaging property and setting outer buildings on fire.While the US had not before Thursday blamed any specific group for the rocket attacks or attributed them to any Iranian proxies in the region, the administration has made clear where it places the ultimate blame.

“We have stated before that we will hold Iran responsible for the actions of its proxies that attack Americans,” State Department spokesman Ned Price said on Monday, noting that “many of these attacks have used Iranian-made, Iranian-supplied weapons.”

Earlier this week, White House spokeswoman Jen Psaki had said the US holds Iran accountable for the actions of its proxies.

A February 15 rocket attack on coalition forces near the Erbil International Airport in Iraqi Kurdistan killed a civilian contractor and injured nine others, including four American contractors and one member of the US military who went through concussion protocol. That day, about 14 rockets were fired toward US and coalition forces in Erbil, in northern Iraq. At the time, Psaki said Biden and his administration “reserve the right to respond in a manner and at a time of our choosing.”

She warned that “we will respond in a way that’s calculated on our timetable, and using a mix of tools, seen and unseen.”

“What we will not do, and what we’ve seen in the past, is lash out and risk an escalation that plays into the hands of Iran by further destabilizing Iraq, and that is our priority,” Psaki added.

That attack was the first of three that came in rapid succession.

Over the weekend, at least four rockets struck Balad Air Base north of Baghdad, where a US defense company works on Iraqi combat aircraft.

Then on Monday, two rockets landed in Bahgdad’s international zone, where many foreign embassies are located. There were no reports of injuries or damage.

Strikes could complicate diplomatic efforts with Iran

The US strikes come as Washington and Tehran position themselves for negotiations about Iran’s nuclear program, potentially complicating an already fragile process.

Iran Foreign Ministry spokesman Saeed Khatibzadeh denied any ties to the February 15 attack in Erbil, and Iran has not claimed responsibility for any of the other strikes. “While these rumors are strongly rejected, the dubious attempt to attribute it to Iran is also strongly condemned,” Khatibzadeh said, according to a February 16 report by Iran’s state official news agency Mehr.

The US strike could create tension with lawmakers who would otherwise back Biden’s agenda and whose support he will need going forward.

“This makes President Biden the fifth consecutive US president to order strikes in the Middle East,” said Rep. Ro Khanna, a California Democrat on the House Foreign Affairs Committee.

“There is absolutely no justification for a president to authorize a military strike that is not in self-defense against an imminent threat without congressional authorization. We need to extricate from the Middle East, not escalate.”

“The President should not be taking these actions without seeking explicit authorization instead of relying on broad, outdated” Authorization for Use of Military Force laws, Khanna said. “I spoke against endless war with Trump, and I will speak out against it when we have a Democratic President.”

The military last struck Kata’ib Hezbollah sites in March 2020, after a rocket attack blamed on the Iranian-backed militia killed two US service members and a British medic and injured 14 others. The attack targeted Camp Taji, an Iraqi base that hosts coalition forces engaged in the fight against ISIS.

In response to the deadly rocket attack, the US struck five sites belonging to Kata’ib Hezbollah that were used for storing advanced weaponry provided by Iran, the commander of Central Command, Gen. Kenneth McKenzie, said at the time.

“We assess that each location stored weapons that could enable lethal operations against US and coalition forces in Iraq. We also assess that the destruction of these sites will degrade Kata’ib Hezbollah’s ability to conduct future attacks,” McKenzie said.