Loud statements of the Kremlin after another failure in Syria addressed to the domestic audience, before which the President of the Russian Federation Vladimir Putin it is important to maintain a macho image. Therefore, the output of the Kremlin with the US Memorandum on flights over Syria in response to downed Syrian su-22 as the last action around the military conflict in the Donbass, is nothing more than a demonstrative gesture.
If to speak about the motives of this decision of Moscow, after the US shot down aircraft of the Syrian air force, it is not even Bashar al-Assad. By and large, I think, but wild anger, Assad long time did not cause the Kremlin. But Russia got involved because in the Syrian war. And now — a loss of face. Same story as with the Donbas: got involved, and now the loss of face. After the Americans shot down the plane — with impunity — Putin inside the country (aka inside — a cool, macho), outside cannot leave it unanswered. Moreover, in this miserable Syrian campaign this is the second downed plane: first, as you know, was shot down by the Turks. So the motives are clear — to save face. This is actually the main and only motive of the entire Russia’s foreign policy: first to climb, and then to save face.
I am sure that there are no direct military confrontation between America and Russia will not. The Americans have decided to change the location of the troops. Both the Americans and the Russians, of course, do not want a head-on collision of American and Russian aircraft. Not even because it is supposedly fraught with thermonuclear war. It absolutely is no war: even if we assume the air battle between American and Russian fighter that is absolutely unbelievable from my point of view, anyway it is still a million miles to the rupture of diplomatic relations and threats of war.
But the point is not just that. Direct military confrontation is a complete collapse of Russian-American relations. And they desperately need Russia. Naturally enough the United States. Look at how more than carefully with formidable external rhetoric take sanctions against Russia — and so they pack what they want, understand this way or that way. To aggravate relations with Russia just so the Americans will not. And American pilots and Russian air defense would be to behave very carefully.