Who let them in? Assad. Nobody else is there on any legal basis, including us. Turkey flies air raids into Syria daily.
In any case, the Turks knew whoever it was, it was someone bombing jihadis. That’s the only thing anyone is doing in the air there.
I meant, who let them into NATO. I agree with your point completely.
The Russians have been assisting assad from the air to retake some land at the north western border from some Turkmen tribes. These are no jihadis, certainly not isis. The targeting of the Turkmen must be designed to draw NATO into the fight. Putin is very astute and has no love for the west, just remember the whole Ukraine/ sanctions thing.