In what is being characterized as an act sure to further escalate already alarming tensions between the United States, Syria, and Russia, an American fighter jet shot down a Syrian warplane over Raqqa on Sunday, prompting Moscow to cut off its deconfliction channel with the U.S.

"As of June 19 this year, the Defense Ministry of the Russian Federation has ended its interaction with the U.S. side under a memorandum for preventing incidents and providing for safe flights during operations in Syria and demands that the U.S. command carry out a careful investigation and report about its results and the measures taken," a statement from Moscow reads.

The Defense Ministry continued:

The shooting down of a Syrian Air Force jet in Syria's airspace is a cynical violation of Syria’s sovereignty. The US' repeated combat operations under the guise of 'combating terrorism' against the legitimate armed forces of a UN member-state are a flagrant violation of international law, in addition to being actual military aggression against the Syrian Arab Republic.

The U.S. decision to shoot down the Syrian warplane—which, according to American officials, was retaliation against the plane's bombing of nearby U.S.-backed ground troops—came "on the same day that Iran's Revolutionary Guards Corps launched several midrange missiles from inside Iran at targets in Syria, hoping to punish Islamic State forces responsible for last week’s terrorist attacks in Tehran," the New York Times reported.

The move, the Times noted, marks "the first time the American military has downed a Syrian aircraft since the start of the civil war in 2011."

The Pentagon issued a statement: "The coalition does not seek to fight Syrian regime, Russian, or pro-regime forces partnered with them, but will not hesitate to defend coalition or partner forces from any threat."

According to the Associated Press, the Pentagon's efforts to de-escalate following the strike do not appear to have been successful: "Russia says it will treat US-led coalition planes in Syria, west of the Euphrates, as targets after US downed Syrian jet."

Here is what the Russian Defense Ministry said: "Any aircraft, including planes and drones of the international coalition, detected in the operation areas west of the Euphrates River by the Russian air forces will be followed by Russian ground-based air defense and air defense aircraft as air targets."

Following these developments, commentators have expressed alarm at the possibility that President Donald Trump could escalate matters even further, given his erratic and impulsive behavior in addition to his inexperience and lack of education on matters of foreign policy.

There is an enormous risk of miscalculation and mistakes now—on both sides. Trump's erratic impulsiveness is a national security risk. https://t.co/UT11dZ2Uj2 — Brian Klaas (@brianklaas) June 19, 2017

It'd be nice to have some adults in charge right about now. https://t.co/vA7g2G93z9 — emptywheel (@emptywheel) June 19, 2017

As Common Dreams has reported, Trump in April ordered missile strikes against a Syrian airbase in a move denounced as "an illegal act of war."

Similar criticism was leveled following the downing of the Syrian warplane on Sunday.