The US carried out an airstrike on a weapons warehouse in eastern Syria used by Iranian-backed militias, in retaliation for what has been a growing number of attacks on bases housing US troops in the region for the past several weeks, the Pentagon said.

In Wednesday’s strike, two US F-15 fighter jets dropped multiple bombs on a weapons storage facility near Maysulun in Deir Ezzor that was known to be used by Iran’s Revolutionary Guard, US officials said.

“The President has no higher priority than the safety of US personnel, and he directed today’s action to make clear that the United States will defend itself, its personnel, and its interests,” Defense Secretary Lloyd Austin said in a statement.

A military official told reporters in a call that people were seen at the warehouse during the day as the US military watched the site for hours, but the number decreased to about “a couple” overnight when the strike occurred. The official said the strike triggered secondary explosions, indicating the presences of weapons, but the US believes that no civilians were killed and any people at the warehouse were tied to the Revolutionary Guard or militia groups.

The strike, said a senior defense official also on the call, was aimed at “disrupting and degrading the capabilities of groups directly responsible for attacking US forces in the region” by specifically targeting facilities associated with the Revolutionary Guard. Both officials spoke on condition of anonymity to provide an assessment of the strike.