Royal Air Force Typhoon jets have conducted a mission with French aircraft in a coordinated attack targeting an underground arms cache in Syria used by the Daesh militant organization, according to the UK's MoD.
The site, identified by intelligence, was assessed as storing arms and explosives, the statement said, and was situated in mountainous terrain just to the north of Palmyra in Syria's central region.
"Our aircraft employed Paveway IV guided bombs to target a number of access tunnels down to the facility... preliminary assessments suggest the objective was successfully hit," the MoD said.
There was no indication of any civilian casualties in the operation late on Saturday and every plane involved returned safely, the MoD added.
The Typhoon fighters were supported by a Voyager refuelling tanker.
IS - alternatively referred to as the so-called Islamic State - enforced extremist governance over large swathes of Iraq and Syria until 2019.
"This action shows British leadership, and determination to stand shoulder to shoulder with our allies, to stamp out any re-emergence of the terrorist group and their violent and radical beliefs in the Middle East," UK Defence Secretary John Healey stated.
RAF aircraft have conducted overwatch operations over Syrian airspace to "deter any attempted resurgence" of IS following its defeat at the climactic battle in Baghuz in 2019, the ministry said.
"I want to thank every member of the UK armed forces participating in this strike for their expertise and their courage," he added. "They were part of thousands of British troops on duty over the holidays. This operation, to remove terrorist threats who threaten our way of life, demonstrates how our armed forces are prepared to act, all year round, protecting the UK within its borders and influential overseas."
In December, the US military conducted what it described as a "major assault" against IS targets in the country, following an attack killed two US servicemembers and a civilian linguist in Palmyra.
The UN estimates IS still has between 5,000 and 7,000 fighters in Syria and Iraq.
