Russian Prime Minister Vladimir Putin wa

The Russian military issued a stark warning to the United States on Monday, saying they are prepared to shoot down any coalition aircraft or unmanned drones operating in certain parts of Syria, reports Fox News.

The Russian defense ministry told western coalition forces they are now viewing any aircraft operating west of the Euphrates River as valid "targets.”

“Any aircraft, including the international coalition’s planes and drones, discovered west of the river Euphrates, will be accompanied by ground and air-based anti-aircraft defenses as aerial targets,” said the official statement from Moscow.

The provocative threat comes just days after the United States Air Force shot down a Syrian fighter jet operating inside a “de-confliction zone” established by American officials; the first time the US has engaged in air-to-air combat in nearly 20 years.

The Russian air force has been providing air-support and coverage for the al-Assad regime since 2015, and frequently coordinates with western coalition forces to avoid unnecessary military incidents and collateral damage. 

Russian officials harshly condemned the US attack on the Syrian jet, saying coalition forces were “helping the terrorists that the U.S. is fighting against […] What is this, if not an act of aggression?”