RAF Typhoon fighter aircraft have conducted a mission with France's air force in a coordinated attack on an underground arms cache in Syrian territory employed by the IS group, according to the UK's MoD.
The facility, identified by surveillance, was assessed as housing weapons and explosive materials, the announcement noted, and was situated in mountains just above the ancient city of Palmyra in the heart of Syria.
"Our fighter planes employed precision-guided Paveway IV munitions to target a number of approach shafts providing entry to the depot... preliminary assessments are that the strike was effective," the ministry announced.
There was no evidence of any harm to civilians in the strike on Saturday evening and every plane involved returned to base without incident, the MoD added.
The Typhoon FGR4s were assisted by a Voyager tanker plane.
IS - also known as ISIS - enforced militant control over parts of both Syria and Iraq prior to its 2019 collapse.
"This action demonstrates our UK leadership, and commitment to work closely with allied nations, to eliminate any revival of IS and their violent and radical beliefs in the Middle East," Britain's Defence Chief John Healey remarked.
UK warplanes have conducted patrols over Syria to "prevent any attempted resurgence" of IS after its military defeat at the Baghuz confrontation in 2019, the ministry said.
"I must thank every member of British forces participating in this operation for their expertise and their valour," Healey added. "They were among thousands of British personnel on duty over Christmas and New Year. This operation, to take out terrorist threats who endanger our safety, shows how UK forces are ready to step up, continuously, keeping Britain secure at home and powerful internationally."
Last December, the United States armed forces carried out what it termed a "massive strike" targeting Daesh sites in the country, after an ambush claimed the lives of two US servicemembers and a civilian interpreter in Palmyra.
The United Nations reports Islamic State still has an estimated 5,000 to 7,000 fighters in both countries.
