The risk of American/Russian clash in Syria

At some point in the disaster country of Syria there's going to be a firefight between US troops and Russian troops. It may have already happened. When the Syrian Democratic Forces backed by US airstrikes and artillery defended themselves very robustly after being attacked by pro-Syrian regime fighters near the Euphrates river last week, 100 of the attackers died. That is turkey shooting slaughter. No one knows why this regime force suddenly appeared with tanks and artillery and took on the SDF when they must have known that the Americans were around. But did this force have Russians amongst them? The chances are there were, but Moscow is being vey careful not to admit anything. There's casual talk about maybe some Russian mercenaries. That word has a multiplicity of meanings. In eastern Ukraine for example it means Russian Spetnaz special forces. In Syria it probably means fully-fledged Russian troops but never to be confirmed by Moscow because of the embarrassment of such a wholesale defeat. So far the American and Russian fighter jets filling the skies over Syria have miraculously managed to avoid crashing into each other or firing air-to-air missiles at each other. The daily deconfliction arrangement has worked. So well done the Pentagon and the Russian defence ministry. But we're entering a dangerous phase in the Syria conflict, with the big boys - the US, Russia, Syria, Turkey and Iran - trying to carve out their territory. A major clash between any of them could happen on the ground almost any day although last week's massive firefight must have been a terrifying lesson. They won't do that again in a hurry. Moscow should have been on the phone to Assad to say, "what the hell are you doing?" But if there WERE Russians among those killed, does that mean Putin and co knew about it beforehand and approved? Was this supposed to be a test for America's nerve? If so they badly miscalculated. Self defence is a basic right for the military whatever the circumstances, and I reckon whoever was in charge decided that as soon as the Syrian regime force appeared, a massive display of firepower was required. Jim Mattis, the US Defence Secretary, has denied last week's clash meant there was mission creep in Syria. His message was then made clear: "If we're attacked we have the right to defend ourselves." And didn't they just!