Royal Air Force Typhoon jets have conducted a mission with French aircraft in a coordinated attack against an underground arms cache in Syria operated by the IS group, according to the UK's MoD.
The site, identified by reconnaissance, was assessed as storing arms and explosives, the statement said, and was located in mountainous terrain just above the ancient city of Palmyra in central Syria.
"The RAF jets used precision-guided Paveway IV munitions to hit a several approach shafts down to the facility... early reports indicate the objective was successfully hit," the ministry announced.
There was no indication of any civilian impact in the attack late on Saturday and all the aircraft returned safely, the defence officials confirmed.
The Typhoon fighters were backed up by a Voyager tanker plane.
Daesh - also known as Daesh - enforced extremist governance over significant areas in Syria and Iraq until 2019.
"This action shows British leadership, and resolve to operate in unison with allied nations, to eliminate any re-emergence of Daesh and their harmful and extremist ideologies in the region," Britain's Defence Chief the minister said.
British military aircraft have performed overwatch operations over Syrian airspace to "prevent any attempted comeback" of Islamic State following its military defeat at the climactic battle in Baghuz in 2019, the ministry said.
"I must thank the personnel of British forces participating in this mission for their skill and their bravery," the Defence Secretary said. "They were part of numerous British troops stationed over the festive period. This action, to remove dangerous terrorists who pose a risk to our security, shows how UK forces are prepared to act, all year round, keeping Britain secure at home and influential overseas."
In December, the United States armed forces executed what it described as a "massive strike" against IS targets in the country, following an attack claimed the lives of two American soldiers and a local interpreter in the Palmyra area.
The United Nations estimates Daesh still maintains an estimated 5,000 to 7,000 combatants in both countries.
