DAMASCUS and Moscow condemned Thursday night’s US air strike on Syrian troops yesterday, calling it “state terrorism.”

Lebanon’s al-Masdar News website reported that six Syrian troops had been killed in the attack, while two tanks and an anti-aircraft vehicle were destroyed.

The US-led Inherent Resolve coalition — which includes British forces — confirmed that it had attacked Syrian troops who were pushing back US-supported Free Syrian Army (FSA) insurgents towards the southern at-Tanf border crossing with Iraq.

A coalition statement claimed that jets had fired “warning shots” that “posed a threat to US and partner forces” occupying the remote border post.

It claimed that the planes had attacked after “apparent” Russian attempts to persuade the army to retreat. But the Syrian military rejected the Pentagon’s justification for the “blatant” aggression.

“The Syrian Arab Army is fighting terrorism on its territory,” a military source said. “No party whatsoever has the right to determine the course and destination of the army’s operations against the terrorist organisations, mainly Isis and al-Qaida.”

“Those who claim to be fighting them should direct strikes against them and not against the Syrian Arab Army.”

An anonymous US defence official told the US military’s Stars and Stripes newspaper that Moscow and Washington had an agreement that no Syrian forces could come within 34 miles of at-Tanf.

But Russian Foreign Minister Sergey Lavrov responded: “Whatever the reason for the US command to make this decision, this strike is illegitimate and unlawful.”

US and British troops have been training and arming FSA militants at bases in northern Jordan.

But reports emerged this week that US forces had entered Syria in support of a new FSA push to seize the eastern province of Deir Ezzor from Isis — which would give them control of oil and gas fields and the border with Syria’s ally Iraq.

In the wake of the US attack, several FSA factions and the larger Ahrar as-Sham group reportedly pulled out of UN-hosted peace talks in Geneva.

Russia’s Sputnik news agency said it had seen a memo from the groups dated Thursday saying that they were quitting the Saudi-based High Negotiations Committee bloc of jihadist forces on the grounds that it “doesn’t serve the Syria revolution.”

Syrian ambassador to the United Nations and chief negotiator Bashar al-Ja’afari said the US air strike had been raised at the talks.

“At every meeting, we would like to remind the attendees that state terrorism is being practised against our country,” he told reporters.