(BBC) Russia has warned the US-led coalition fighting in Syria that it will view its aircraft as targets, after a Syrian military plane was shot down.
The coalition said it had shot down the Syrian Su-22 after it bombed US-backed fighters in Raqqa province on Sunday.
Russia, Syria’s main ally, said it was also halting communications with the US aimed at preventing air incidents.
Syria condemned America’s “flagrant attack”, saying it would have “dangerous repercussions”.
The incident comes at a time when the US-led coalition and the fighters its supporting on the ground are battling to oust so-called Islamic State (IS) from its Syrian stronghold of Raqqa.
How has Russia responded?
“Any aircraft, including planes and drones belonging to the international coalition operating west of the Euphrates river, will be tracked by Russian anti-aircraft forces in the sky and on the ground and treated as targets,” the Russian defence ministry said.
It denied the US had used a communications channel before the Su-22 fighter bomber was downed.
The memorandum of co-operation with the coalition aimed at preventing air incidents and guaranteeing flight safety was ending as of Monday, the defence ministry added.
It is not the first time communications have been suspended between the two sides – in April, the hotline was shut down after the US launched 59 Tomahawk cruise missiles at Syria’s Shayrat airbase in response to a suspected chemical weapons attack on a rebel-held town in Idlib province.
But the US and Russia had agreed to resume communications last month.
Why are air combat kills so rare?
A line in the sky: analysis by Jonathan Marcus, BBC defence and diplomatic correspondent
Russia’s ministry of defence has responded sharply. In addition to the usual rhetoric – the charge that the US is violating Syrian sovereignty and breaking international law – there is a practical step – the immediate suspension of the co-ordination channel set up to avoid clashes between US and Russian forces.
There is a threat too, namely that in areas where Russian aircraft are operating, coalition drones and aircraft west of the Euphrates river will be tracked and “treated as targets”. It should be noted that the co-ordination mechanism has generally worked well and its operation is as much in Moscow’s as Washington’s interest.
A previous “suspension” of the mechanism by Russia seems to have been by word only – behind-the-scenes contacts continued. But as the battle for eastern Syria steps up, Russia and its Syrian government ally seem intent on drawing a line in the sky.
How did the US justify downing the jet?
The Su-22 fighter bomber was engaged by an F/A-18E Super Hornet after it dropped bombs near the town of Tabqa in Raqqa province on Sunday afternoon, the Pentagon said.
It is believed to be the first air-to-air kill of a manned aircraft by a US military jet since the Kosovo campaign in 1999.
The US-backed Syrian Democratic Forces (SDF), who are fighting IS militants as part of a drive to retake the city of Raqqa, were operating in the Tabqa area.
A statement from the US-led coalition’s Operation Inherent Resolve said pro-government militiamen had attacked SDF units, driving them from the town of Ja’Din.
The US-led coalition conducted what it said was a “show of force” – a reported buzzing of the pro-government troops by jets – to stop the attack and then called Russia to try to “de-escalate the situation and stop the firing”.
However, the Su-22 dropped bombs on SDF positions a few hours later, the coalition said, and “in accordance with rules of engagement and in collective self-defence of coalition-partnered forces [the plane] was immediately shot down”.
Attempts to warn the plane away using an emergency radio frequency failed, the US Central Command said.
Both Russia and Syria say the warplane was on a mission against IS, about 40km (25 miles) south-west of Raqqa, when it came under fire.
The Syrian army said the incident would have “dangerous repercussions” on efforts to fight terrorism.
Russia said in its statement that the Syrian pilot had ejected over IS-controlled territory and “his fate remains unknown”.
Why are air combat kills so rare?
Despite Hollywood blockbusters showcasing aerial dogfights, they have almost vanished from modern warfare.
“The era of dogfighting is largely over,” says Justin Bronk, a research fellow at the Royal United Services Institute, specialising in combat airpower.
“After the totally lopsided kill-to-loss ratio attained by the US Air Force and US Navy during the First Gulf War, it is a very rare thing for regimes under attack by the US and its allies to send fighters up in defence – since they know how it will end.”