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.

The site is believed to be used as part of a weapons smuggling operation by the militias. The strikes were carried out to degrade the ability of the groups to carry out future attacks and to send a message about the recent attacks, the US official said.

The decision to target the site in Syria was made from the “top down,” a defense official said, and was not because of a specific recommendation from the military.