Turkey became a member of NATO in 1952 in conjunction with is geographic neighbor and long term rival, Greece. Turkey is a large country with a large population and the only NATO country not in Europe proper but in Asia; except the small area (3% of Turkish land mass) variously called European Turkey, Eastern Thrace or Turkish Thrace. The Turkish military is also quite large; the second largest in NATO.
Strategically, Turkey is the key to southern Europe and essential to NATO’s capacity to control its southern flank. In addition to sharing borders with both the Soviet Union and Bulgaria, Turkey also controls the entrance to the Black Sea through the two important straights, the Bosporus and Dardanelles, thus limiting Soviet ability to influence the Mediterranean. These factors were no doubt a significant factor in NATO’s meek reaction to the Turkish invasion of Cyprus and conflict with Greece in 1974.
Turkey’s relationship with Greece has been a constant source of friction throughout recent history and certainly within NATO, but it’s difficult to say how this would develop under the pressures of conflict. The multi-national NATO command structure was built to ensure that troops, ships or air elements of one would not come under command of the other. Turkey retains command of its land forces through Allied Land Forces South Eastern Europe (LANDSOUTHEAST) headquartered in Izmir, and reporting directly to Allied Forces Southern Europe (AFSouth); Sixth Allied Tactical Air Force (6 ATAF) is also in Izmir and Commander North Eastern Mediterranean (COMEDNOREAST) in Ankara commands its naval forces. Greece has equivalent commands all reporting to Naples.