Surely This Is No Surprise

Also,

The Russian Defense Ministry announced it is halting cooperation with its US counterparts in the framework of the Memorandum on the Prevention of Incidents and Ensuring Air Safety in Syria following the coalition’s downing of a Syrian warplane.

[...]

The actions of the US Air Force are in fact “military aggression” against Syria, the statement adds.

The ministry emphasized that Russian warplanes were on a mission in Syrian airspace during the US-led coalition’s attack on the Syrian Su-22, while the coalition failed to use the communication line to prevent an incident.

[...]

The ministry considers the move “a conscious failure to comply with the obligations under the Memorandum on the Prevention of Incidents and Ensuring Air Safety in Syria,” and is thus halting cooperation with the US within the memorandum framework as of June 19, the statement concluded.

[...]

The US-led coalition downed the Syrian government warplane on Sunday. At the moment of the attack the jet was carrying out operations against Islamic State (IS, formerly ISIS/ISIL) some 40km from Raqqa, the Russian Defense Ministry said. The pilot ejected from the plane above IS-controlled territory and is still missing.

  RT

And what's the US excuse for the attack?

The US-led coalition claims that the Syrian plane was bombing American-backed forces on the ground.

“At 6:43pm, a Syrian regime SU-22 dropped bombs near SDF [Syrian Democratic Forces] fighters south of Tabqah and, in accordance with rules of engagement and collective self-defense of Coalition partnered forces, was immediately shot down by a US F/A-18E Super Hornet,” the Combined Joint Task Force – Operation Inherent Resolve said in a statement.

  RT

I would think that in this delicate situation for which the agreement with Russia was made in the first place, the US would have contacted the Russians. Of course, if the SDF were being bombed, that might constitute emergency measures. Would it be too much to ask to see evidence they were being bombed?

"Near SDF fighters" seems a little vague, especially considering the Syrian claim is that the plane was on an operation against IS.

...but hey, do what you want...you will anyway.