British and French warplanes have carried out an airstrike in central Syria, targeting an underground facility suspected of storing weapons for the Islamic State group

The strikes on Saturday evening hit the site, thought to be used by Isis militants to store weapons and explosives, in a mountainous area north of the Syrian city of Palmyra, according to a statement from the UK government. French jets joined the strikes by RAF Typhoon FGR4s.

Syria has begun circulating new currency bills, a year after Bashar Assad's government fell. Central Bank Governor Mokhles Nazer said Saturday that the exchange of old Syrian pounds with new banknotes has officially started.

Jordan confirmed that its air force took part in the U.S. air strikes "targeting several ISIS positions in southern Syria."

Europe stepped back into the Syrian conflict this week. France and the UK carried out joint and coordinated airstrikes against ISIS targets, signalling a renewed willingness to use military force beyond their borders.

Despite years of defeat claims, ISIS adapts and persists in Syria's chaos, prompting major U.S. military response and raising containment questions.

The airstrikes on ISIS targets are being conducted in response to the killing of two U.S. Army soldiers and an civilian contractor by a lone terrorist in Palmyra, Syria.

The clashes came two days after a bombing at an Alawite mosque in the city of Homs killed eight people and wounded 18 others during prayers.

“If Syria fails to integrate all armed forces and former opposition groups into its army, it faces an existential challenge of fragmentation and disintegration,” Caroline Rose, director of military and national security priorities at the New Lines Institute, told Al Jazeera.