Britain’s and France’s air forces conducted a joint operation on Saturday evening to bomb sites in the mountains north of Syria’s Palmyra.

According to Reuters, Britain’s defense ministry claimed their target was a suspected underground arms cache previously used by ISIS.

Western aircraft have been conducting patrols to stop what they claim is a resurgence of the militant group that ruled parts of Syria until 2019.

“Our aircraft used Paveway IV guided bombs to target a number of access tunnels down to the facility; whilst detailed assessment is now underway, initial indications are that the target was engaged successfully,” Britain’s defense ministry said in a statement.

Britain said it used Typhoon FGR4 combat jets to bomb the target, supported by a Voyager refueling tanker.