U.S. troops based at an oil field in northeastern Syria came under rocket attack Monday, one day afteron facilities used by Iranian-backed militias in the Iraq-Syria border region.
There are no injuries and damage is being assessed. "We will provide updates when we have more information," Operation Inherent Resolve spokesman Colonel Wayne Marotto tweeted Monday afternoon.
U.S. forces used artillery to return fire at the positions from which the rockets were launched.
It was not immediately clear the specific source of the attacks against U.S. forces in Syria.
The rocket attack comes after U.S. airstrikes against facilities used by Iranian-backed militias..
The U.S. "Defensive precision airstrikes" targeted facilities used by militia groups like Kata'ib Hezbollah (KH) and Kata'ib Sayyid al-Shuhada (KSS), according to the Defense Department.
The facilities targeted by the U.S. are engaged in unmanned aerial vehicle or drone attacks against U.S. personnel and facilities in Iraq, the Defense Department said in a statement.
A U.S. official said the locations that were hit included the site from which the drones took off, recovered and were controlled.
The official also said there have been "at least five" drone attacks by Iranian-backed militias against bases in Iraq where U.S. troops, contractors or other personnel are located.
President Biden and members of his Cabinet on Monday cited Article II of the constitution that allows the president to take action to defend U.S. personnel as the authority for conducting the strikes.
"And I directed last night's airstrikes targeting sites used by the Iranian-backed militia groups responsible for recent attacks on the US personnel in Iraq, and I had that authority under Article 2," Mr. Biden told reporters. "And even those up on the Hill who are reluctant to acknowledge that have acknowledged that's the case."
The decision to strike comes as Congress debates whether to reign in presidential war power authority and whether to repeal both the 1991 and 2002 Authorizations of Use of Military Force in Iraq.
The House voted to repeal the 2002 AUMF in Iraq, and the Senate Foreign Relations Committee is expected to debate repealing both authorizations.
Democratic Senator Tim Kaine of Virginia — who has led the effort to repeal the AUMFs — told reporters earlier this month that although the House bill didn't include the 1991 authorization, the House and Senate could meet in conference to craft acceptable legislation.