© Omar haj kadour, AFP | A Syrian army jet fires rockets over the village of Rahbet Khattab in Hama province on March 23, 2017.
The Russian defence ministry said Monday that it was halting aviation cooperation with the United States after the US downed a Syrian government warplane on Sunday, a move one Russian official described as a clear “act of aggression”.
The Russian defence ministry said it was halting cooperation with Washington within the framework of the Memorandum on the Prevention of Incidents and Ensuring Air Safety in Syria, effective immediately. It also accused the United States of not using the proper communication channels before shooting down the Syrian army jet.
"The command of the coalition forces did not use the established communication channel for preventing incidents in Syrian airspace," the ministry said, adding that Moscow "ends cooperation with the American side from June 19".
Moreover, any coalition aircraft flying to the west of the Euphrates will be treated as targets, the defence ministry said.
"Any flying objects, including planes and drones of the international coalition, discovered west of the Euphrates river will be tracked as aerial targets by Russia's air defences on and above ground."
Russia previously suspended the memorandum of understanding on air safety in April to protest against US airstrikes launched in response to a suspected chemical attack.
Russia's deputy foreign minister, Sergei Ryabkov, on Monday firmly condemned the United States for shooting down the Syrian plane, calling it an "act of aggression".
"This strike has to be seen as a continuation of America's line to disregard the norms of international law," Ryabkov told journalists in Moscow on Monday, the TASS news agency reported. "What is this if not an act of aggression?"
Ryabkov said the Kremlin had also warned the United States not to use force against the forces of Syrian President Bashar al-Assad, a longtime Moscow ally.
The incident marked the first time an American fighter jet had taken down a Syrian warplane, which Washington accused of attacking US-backed fighters.
The tensions come as the US-led coalition and allied fighters battle to evict the Islamic State (IS) group from its Syrian stronghold of Raqqa.
>> Read more:MSF says 10,000 Syrians flee Raqqa as battle for the city nears
The Syrian jet was shot down after regime forces engaged fighters from the Syrian Democratic Forces (SDF), an alliance battling IS jihadists with US support, in an area close to Raqqa. The American F/A-18E Super Hornet shot down the Syrian SU-22 around 7pm as it "dropped bombs near SDF fighters" south of the town of Tabqa, the coalition said in a statement.
It said that several hours earlier, regime forces had attacked the SDF in another town near Tabqa, wounding several and driving the SDF from the town.
The coalition said the Syrian warplane had been shot down "in accordance with rules of engagement and in collective self-defence of Coalition partnered forces".
Syria's army disputed the account, saying its plane was hit while "conducting a mission against the terrorist Islamic State group".
It warned of "the grave consequences of this flagrant aggression".
International imbroglio
The SDF entered Raqqa for the first time earlier this month and now holds four neighbourhoods in the east and west of the city.
In a further escalation of military action in Syria, Iran's Revolutionary Guard said it launched a series of missiles into Syria on Sunday in revenge for deadly attacks on its capital that were claimed by the Islamic State group. It said the missiles were "in retaliation" for a June 7 attack on the parliament complex and the shrine of revolutionary leader Ayatollah Ruhollah Khomeini that killed 17 people.
Assad has focused his forces further east, to the oil-rich province of Deir Ezzor, which is largely under IS group control and where government forces are besieged in part of the provincial capital.
Outside of coalition operations, US forces have only once directly targeted the regime – when Washington launched air strikes against an airbase it said was the launchpad for an alleged chemical attack that killed more than 80 civilians in April.
The Kremlin denounced those US strikes as an "aggression against a sovereign state in violation of international law".
Syria's war began in March 2011 with anti-government protests but has since spiralled into a complex and bloody conflict that has killed more than 320,000 people and become a proxy war for regional powers as well as ensnaring the United States and Russia.
Interfax reported that Ryabkov and the US under secretary of state, Thomas Shannon, would meet in St Petersburg on June 23 to discuss persistent tensions in bilateral ties.
(FRANCE 24 with AP, AFP and REUTERS)