Royal Air Force Typhoon jets have joined forces with France's air force in a joint strike against an underground arms cache in Syria employed by the IS group, according to the UK's MoD.
The site, pinpointed through surveillance, was thought to be containing munitions and bombs, the statement said, and was located in mountains just to the north of the ancient city of Palmyra in the heart of Syria.
"Our fighter planes utilized precision-guided Paveway IV munitions to strike a number of approach shafts down to the facility... preliminary assessments suggest the objective was successfully hit," the MoD said.
There was no sign of any harm to civilians in the attack on Saturday evening and every plane involved returned to base without incident, the defence officials confirmed.
The Typhoon FGR4s were backed up by a Voyager aerial refuelling aircraft.
IS - referred to as Daesh - established extremist governance over significant areas in Syria and Iraq before its territorial defeat in 2019.
"This operation demonstrates British leadership, and resolve to stand shoulder to shoulder with our allies, to eradicate any re-emergence of IS and their dangerous and violent ideologies in the area," UK Defence Secretary John Healey said.
RAF aircraft have carried out patrols over Syrian airspace to "deter any attempted resurgence" of IS following its defeat at the battle of Baghuz in the year 2019, the ministry said.
"I must thank every member of the UK armed forces involved in this mission for their skill and their bravery," Healey added. "Including them were thousands of British troops deployed over the holidays. This action, to remove militants who pose a risk to our safety, shows how UK forces are prepared to act, all year round, keeping Britain secure at home and influential overseas."
Last December, the US military carried out what it termed a "massive strike" on Islamic State objectives in the country, following an ambush killed two American soldiers and a civilian linguist in the Palmyra area.
The UN says IS still has roughly 5-7 thousand fighters in Iraq and Syria.
