"Multiple military actions of USA aviation under the guise of fighting terrorism against the legal military of a state that is a member of the United Nations are a flagrant violation of worldwide law and constitute de facto military aggression against the Syrian Arab Republic", the ministry said, according to The Washington Post. On the other hand, Russian Federation has termed strengthening of USA military in souther Syria as unlawful.
UN Secretary-General Antonio Guterres warned that the incidents could be "very dangerous" and lead to an escalation of the war.
Moscow also halted a military hotline with Washington over the incident, meant to prevent confrontations in Syria's crowded air space.
The jihadists are under major pressure in Syria and neighbouring Iraq.
A temporary suspension was declared on Tuesday after Russian Federation warned it would treat aircraft from the US-led coalition as potential targets.
A defense official also said that it was an act of self-defense as the drone was armed and within a range of striking US-led coalition troops.
In the latest sign of increasingly frequent confrontation with Damascus and its allies, Tuesday's incident closely followed Sunday's U.S. downing of a piloted Syrian army jet in the southern Raqqa countryside after it dropped bombs near US-backed forces. That is where US forces have been training and advising local Syrian Arabs for the fight against Islamic State militants.
Moscow is certainly angry the United States downed the Syrian Su-22 jet, but no one is ready to start a war with America over the issue. This initiative is argued to impose because it's been 6 years that the nation is at war, and this step of ending all combat actions in the region for 2 days will sustenance of national reunion after several years of violence, says a Syrian official.
The American side knows Russia's position, Zakharova said.
The SDF is now trying to enact a siege of the city by taking the southern bank.
Meanwhile, Syria has slammed the incident as a "flagrant attack". Back then it looked absurd, he said.
More than 320,000 people have been killed since Syria s conflict began with anti-government demonstrations in March 2011.
The two countries have noted with growing concern the renewed strength of the Assad regime in southern Syria, particularly in regards to the role played by Iran. "I don t want to create false expectations about immediate results" from the upcoming round of negotiations.