The Pentagon said Thursday night that it launched airstrikes in eastern Syria that targeted two facilities “used by Iran’s Islamic Revolutionary Guard Corps (IRGC) and affiliated groups,” a significant escalation that makes a regional war more likely amid Israel’s bombardment of Gaza.

Secretary of Defense Lloyd Austin said in a statement that the strikes were in response to the series of rocket and drone attacks that have targeted US bases in Iraq and Syria in recent weeks, which the US is blaming on “Iranian-backed militias,” referring to Shia militias that operate in the region.

“These precision self-defense strikes are a response to a series of ongoing and mostly unsuccessful attacks against US personnel in Iraq and Syria by Iranian-backed militia groups that began on October 17,” Austin said.

The US has said Iran is responsible for the attacks on US troops, although the Pentagon acknowledged it has no evidence Iran directed them. The Shia militias are also known to act independently. A US official recently told CNN that how willing those groups are to act independently is a “persistent intelligence gap” for the US.

The spate of attacks on US forces in Iraq and Syria was due to President Biden’s full-throated support for Israel’s onslaught on Gaza. Earlier on Thursday, the Pentagon said it was deploying an additional 900 troops to the Middle East as part of its plans to bolster air defenses in the region.

US troops based in Iraq and Syria have come under rocket and drone attacks over a dozen times since last week, resulting in at least 21 injuries. Pentagon spokesman Brig. Gen. Pat Ryder said 19 troops had been diagnosed with traumatic brain injuries.

This article was originally featured at Antiwar.com and is republished with permission.