Russia, Syria's main ally, has threatened U.S. coalition planes following the downing of a Syrian Su-22 bomber plane on June 18.
The Russian defense ministry said in a statement: "Any aircraft, including planes and drones belonging to the international coalition operating west of the River Euphrates, will be tracked by Russian anti-aircraft forces in the sky and on the ground and treated as targets," notes BBC News.
Russia also said that it was closing down a coordination channel with the U.S. that was meant to prevent air incidents with the U.S. coalition. Russia insisted that the U.S. had not communicated via the channel before shooting down the Su-22.
The Su-22 reportedly dropped bombs near the town of Tabqa in the Raqqa province before it was shot down; U.S.-supported Syrian Democratic Forces are battling ISIS in Raqqa.
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Syria condemned the "flagrant attack" against its plane and warned of "dangerous repercussions."
Russia also shut down the coordination channel with the U.S. after President Donald Trump ordered 59 Tomahawk cruise missiles to be launched at the Shayrat airbase in Syria in April.
In response to Russia's latest threat, Democratic Sen. Chris Murphy of Connecticut tweeted: "Four direct engagements w Syria/Iran/Russia in 45 days. Trump is quietly starting a new war that Congress has not declared. Red alert."
The Trump administration defended the downing of the Su-22 by saying that it had dropped bombs and was engaged with a F/A-18E Super Hornet plane.
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The U.S. coalition's Operation Inherent Resolve said that the incident began when pro-Syrian government militiamen attacked SDF units and drove them out of Ja'Din.
The U.S. coalition reportedly buzzed the pro-Syrian troops with planes in a "show of force" to stop the militiamen's attack and told Russia to "de-escalate the situation and stop the firing."
However, that effort was rebuffed by the Su-22, which dropped bombs a few hours later near SDF positions, according to the U.S. coalition.
The U.S. Central Command said the Su-22 had been warned on an emergency radio frequency.
The U.S. coalition said it responded "in accordance with rules of engagement and in collective self-defense of coalition-partnered forces [the plane] was immediately shot down."
Russia and Syria insisted that the Su-22 was actually on a bombing mission against ISIS when it was shot down.
According to Russia, the pilot ejected over ISIS territory and "his fate remains unknown."
Justin Bronk, a research fellow at the Royal United Services Institute, told BBC News why aerial dogfights are so rare these days:
The era of dogfighting is largely over. After the totally lopsided kill-to-loss ratio attained by the U.S. Air Force and U.S. Navy during the First Gulf War, it is a very rare thing for regimes under attack by the U.S. and its allies to send fighters up in defense -- since they know how it will end.