British Air Force Typhoon fighter aircraft have conducted a mission with French warplanes in a joint strike on an subterranean weapons facility in Syrian territory employed by the Daesh militant organization, according to the UK Ministry of Defence.
The site, identified by intelligence, was believed to be storing arms and explosives, the statement said, and was situated in mountainous terrain just above the ancient city of Palmyra in the heart of Syria.
"Our fighter planes utilized Paveway IV guided bombs to hit a several entry passages providing entry to the depot... preliminary assessments are that the strike was effective," the MoD said.
There was no sign of any civilian casualties in the operation late on Saturday and every plane involved returned safely, the defence officials confirmed.
The Typhoon fighters were assisted by a Voyager refuelling tanker.
The Islamic State group - alternatively referred to as Daesh - established jihadist rule over significant areas in Syria and Iraq until 2019.
"This action underscores the UK's leading role, and commitment to operate in unison with our allies, to eradicate any re-emergence of Daesh and their harmful and extremist ideologies in the Middle East," UK Defence Secretary John Healey remarked.
RAF aircraft have conducted patrols over Syrian airspace to "deter any attempted resurgence" of the group following its military defeat at the battle of Baghuz in 2019, the ministry said.
"I must thank the personnel of British forces participating in this operation for their expertise and their courage," he commented. "Including them were a great many UK service members on duty over the holidays. This mission, to remove dangerous terrorists who endanger our way of life, demonstrates how our armed forces are always on standby, throughout the year, protecting the UK within its borders and influential overseas."
In December, the American forces carried out what it described as a "large-scale strike" against Daesh sites in Syria, after an assault resulted in the deaths of two American soldiers and a civilian interpreter in Palmyra.
The United Nations estimates Daesh still has roughly 5-7 thousand fighters in Iraq and Syria.
