RAF Typhoon jets have joined forces with French warplanes in a coordinated attack against an underground arms cache in Syria employed by the Daesh militant organization, according to the UK's MoD.
The site, located using intelligence, was believed to be storing arms and explosives, the statement said, and was positioned in mountains just to the north of the historic site of Palmyra in the heart of Syria.
"Our aircraft used laser-guided Paveway IV weapons to hit a number of entry passages leading to the depot... initial indications are that the objective was successfully hit," the MoD said.
There was no sign of any civilian casualties in the operation on Saturday evening and all the aircraft returned safely, the MoD added.
The Typhoon fighters were backed up by a Voyager refuelling tanker.
IS - referred to as Daesh - enforced extremist governance over significant areas in Iraq and Syria before its territorial defeat in 2019.
"This operation shows British leadership, and determination to operate in unison with our partners, to eliminate any re-emergence of Daesh and their violent and radical beliefs in the area," the British Defence Secretary the Defence Secretary said.
RAF aircraft have carried out overwatch operations over Syrian airspace to "prevent any efforts to regroup" of IS following its military defeat at the climactic battle in Baghuz in 2019, the ministry said.
"I must thank all the members of our armed forces involved in this mission for their skill and their courage," he added. "Including them were thousands of UK service members stationed over the holidays. This mission, to take out terrorist threats who threaten our way of life, shows how our armed forces are ready to step up, throughout the year, keeping Britain secure domestically and powerful internationally."
Last December, the United States armed forces carried out what it termed a "major assault" on Islamic State objectives in Syria, after an attack resulted in the deaths of two American soldiers and a civilian interpreter in Palmyra.
The UN says Islamic State still has an estimated 5,000 to 7,000 militants in Syria and Iraq.
