British Air Force Typhoon fighter aircraft have conducted a mission with France's air force in a coordinated attack on an underground arms cache in Syria operated by the IS group, according to the UK Ministry of Defence.
The facility, located using reconnaissance, was thought to be housing weapons and explosive materials, the statement said, and was situated in hills just north of the historic site of Palmyra in the heart of Syria.
"Our fighter planes employed laser-guided Paveway IV weapons to hit a number of approach shafts down to the site... early reports indicate the target was engaged successfully," the MoD said.
There was no evidence of any harm to civilians in the operation late on Saturday and every plane involved returned to base without incident, the MoD added.
The Typhoon FGR4s were backed up by a Voyager refuelling tanker.
IS - referred to as the so-called Islamic State - enforced militant control over parts of both Syria and Iraq prior to its 2019 collapse.
"This strike demonstrates British leadership, and commitment to stand shoulder to shoulder with our allies, to eliminate any resurgence of the terrorist group and their violent and radical beliefs in the area," the British Defence Secretary the minister said.
RAF aircraft have performed overwatch operations over Syrian airspace to "forestall any attempted comeback" of IS after its routing at the battle of Baghuz in the year 2019, the MoD reported.
"I must thank all the members of our armed forces involved in this strike for their skill and their bravery," the Defence Secretary said. "They were part of a great many British troops stationed over the holidays. This action, to eliminate dangerous terrorists who pose a risk to our security, shows how our armed forces are ready to step up, all year round, ensuring Britain's security within its borders and influential overseas."
Last December, the American forces executed what it described as a "massive strike" on Islamic State objectives in the country, following an assault killed two US servicemembers and a civilian interpreter in Palmyra.
The UN reports IS still boasts between 5,000 and 7,000 militants in Syria and Iraq.
