Turkey is strategic politically and geographically. It holds the choke point of the Russian Black Sea fleet.
Erdogans knows how to play the Russians against the US to his benefits. See how he sided with China and Russia over Venezuela.
Also very gutsy by shooting down that Russian Su-24 over Syria and talked tough to Putin. Now buying Russian sophisticated air defence systems thumbing his nose at Trump who wants Turkey to buy the Patriot rubbish missiles that are more a threat to those launching them.
