US Air Force A-10 Thunderbolt-2 fighter jets
© Hamad I Mohammed / Reuters
The US-led coalition inside Syria says that it has destroyed pro-government forces that entered the deconfliction zone established by the United States and Russia around a coalition training facility. The coalition last struck a pro-government convoy in the area on May 18.

"The Coalition destroyed additional pro-Syrian regime forces that advanced inside the well-established deconfliction zone in southern Syria," said a statement from the US Central Command.

"The Coalition does not seek to fight Syrian regime or pro-regime forces but remains ready to defend themselves if pro-regime forces refuse to vacate the deconfliction zone."

At least two Syrian army servicemen were killed and more than 15 were injured as a result of the fresh airstrikes by the US-led coalition in the At Tanf area, according to the source.

The deconfliction zone, with a radius of about 55 km, was established around the town of At Tanf, where the US has set up base to train special forces for the final assault on the Islamic State stronghold of Raqqa.

"Despite previous warnings, pro-regime forces entered the agreed-upon deconfliction zone with a tank, artillery, anti-aircraft weapons, armed technical vehicles and more than 60 soldiers posing a threat to the Coalition and partner forces based at the At Tanf Garrison," said the CENTCOM statement. "The Coalition issued several warnings via the deconfliction line prior to destroying two artillery pieces, an anti-aircraft weapon, and damaging a tank."

On May 18, the Coalition attacked a convoy of what the US called "Iranian-directed troops," who were moving in the direction of the training base, which houses several hundred US staff.

The bombardment was condemned by Damascus, which has repeatedly accused Washington and its allies of operating within its sovereign territory, and Moscow, which according to media reports, had tried to prevent the escalation of the standoff, relaying messages between the two sides.

The American attack occurred on the same day US-backed militias launched an all-out assault on Raqqa which has served as the Islamic State's unofficial "capital" since its capture in 2014. Raqqa is located 300 km to the north of At Tanf.

The battle for the city, where up to 4,000 ISIS fighters are still thought to be holed up, is expected to be quicker than the siege of Mosul, where fighting still continues eight months after the initial assault began. The International Rescue Committee says that 200,000 civilians are still trapped in Raqqa.

"The strike delivered by the coalition led by the United States is a direct entry of the coalition into an open military conflict in Syria," First Deputy Chairman of the Russian Federation Council's Committee on Defense and Security Frants Klintsevich said.

"This is an act of aggression, Russia will immediately raise the issue of an extraordinary convocation of the UN Security Council," Klintsevich stressed.

Russia will continue efforts aimed at reconciliation and the creation of zones of de-escalation in Syria despite a fresh strike on pro-government forces by US-led coalition, a senior Russian lawmaker told Sputnik on Tuesday.

"After the provocation in Idlib, this was to be expected, although we hoped that common sense would prevail," head of State Duma's Committee on International Affairs Leonid Slutsky said.

"Obviously, the [US] moves not against the terrorists, but against [Syrian President Bashar] Assad, unfortunately, continue. We, on our part, will continue the course aimed at reconciliation and the creation of zones of de-escalation," Slutsky stressed.