The US military on Thursday carried out strikes against two facilities in eastern Syria used by Iran’s Islamic Revolutionary Guard Corps and groups it backs, the Pentagon said, in response to a spate of attacks against US forces in both Iraq and Syria.

According to Reuters, US and coalition troops have been attacked at least 12 times in Iraq and four times in Syria by Iran-backed forces.

A total of 21 US forces have suffered minor injuries, the vast majority of them traumatic brain injuries.

“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,” US Defense Secretary Lloyd Austin said in a statement.

The strikes were ordered by President Joe Biden.