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

The strikes mark the military’s first known action under President Joe Biden. The site was not specifically tied to the rocket attacks, but were believed to be used by Iranian-backed Shia militias operating in the region.

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

Pentagon Press Secretary John Kirby

At President Biden’s direction, U.S. military forces earlier this evening conducted airstrikes against infrastructure utilized by Iranian-backed militant groups in eastern Syria. These strikes were authorized in response to recent attacks against American and Coalition personnel in Iraq, and to 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 Kait’ib Hezbollah (KH) and Kait’ib Sayyid al-Shuhada (KSS).

This proportionate military response was conducted together with diplomatic measures, including consultation with Coalition partners. The operation sends an unambiguous message: President Biden will act to protect American and 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.”