RAF Typhoon jets have conducted a mission with France's air force in a joint strike against an underground arms cache in Syria operated by the IS group, according to the UK's MoD.
The facility, identified by intelligence, was thought to be containing munitions and bombs, the statement said, and was situated in mountains just to the north of Palmyra in Syria's central region.
"Our fighter planes utilized laser-guided Paveway IV weapons to target a series of access tunnels down to the facility... early reports indicate the objective was successfully hit," the ministry announced.
There was no evidence of any civilian casualties in the attack late on Saturday and each participating jet made a safe return, the defence officials confirmed.
The Typhoon FGR4s were backed up by a Voyager refuelling tanker.
The Islamic State group - also known as Daesh - enforced militant control over significant areas in Syria and Iraq prior to its 2019 collapse.
"This strike shows the UK's leading role, and determination to work closely with allied nations, to eradicate any revival of IS and their dangerous and violent ideologies in the region," Britain's Defence Chief the minister stated.
RAF aircraft have performed surveillance missions over Syrian airspace to "deter any efforts to regroup" of the group following its military defeat at the Baghuz confrontation in 2019, the authorities noted.
"I want to thank all the members of the UK armed forces involved in this mission for their professionalism and their bravery," Healey said. "They were among a great many UK service members deployed over the holidays. This action, to eliminate militants who threaten our security, highlights how UK forces are prepared to act, throughout the year, protecting the UK within its borders and strong abroad."
During December, the US military conducted what it described as a "major assault" on Islamic State objectives in Syria, subsequent to an attack claimed the lives of two US troops and a civilian interpreter in the Palmyra area.
The United Nations reports Islamic State still boasts between 5,000 and 7,000 militants in Syria and Iraq.
