Turkey is still (nominally) in NATO. But why? This kind of crap ought to be plenty of grounds for expulsion.
While only a small part of Turkey is in Europe, They have a very strategic location controlling the Turkish Straits, Bosporus, Sea of Marmara, Dardanelles... that link the Black and Aegean Seas to the Med.
They have the worlds 10 largest military, bigger than most EU nations. They would be fully susceptible to Russia if the NATO nations did not protect them.
Basically, they are playing both ends against the middle, geographically speaking, which they have always controlled.