Turkey is re-emerging as a significant regional power. In some sense, it is in the process of returning to its position prior to World War I when it was the seat of the Ottoman Empire. But while the Ottoman parallel has superficial value in understanding the situation, it fails to take into account changes in how the global system and the region work. Therefore, to understand Turkish strategy, we need to understand the circumstances it finds itself in today.
The end of World War I brought with it the end of the Ottoman Empire and the contraction of Turkish sovereignty to Asia Minor and a strip of land on the European side of the Bosporus. That contraction relieved Turkey of the overextended position it had tried to maintain as an empire stretching from the Arabian Peninsula to the Balkans. In a practical sense, defeat solved the problem of Turkey's strategic interests having come to outstrip its power. After World War I, Turkey realigned its interests to its power. Though the country was much smaller, it was also much less vulnerable than the Ottoman Empire had been.
The Russia Problem
At the same time, a single thread connected both periods: the fear of Russia. For its part, Russia suffered from a major strategic vulnerability. Each of its ports -- St. Petersburg, Vladivostok, Murmansk and Odessa -- was accessible only through straits controlled by potentially hostile powers. The British blocked the various Danish straits, the Japanese blocked access to Vladivostok and the Turks blocked access to the Mediterranean. Russian national policy had an ongoing focus of gaining control of the Bosporus both to prevent a blockade and to project power into the Mediterranean.
Therefore, the Russians had a particular interest in reshaping Turkish sovereignty. In World War I, the Ottomans aligned with the Germans, who were fighting the Russians. In the inter-war and World War II periods, when the Soviets were weak or distracted, Turkey remained neutral until February 1945, when it declared war on the Axis. After the war, when the Soviets were powerful and attempted covert operations to subvert both Turkey and Greece, the Turks became closely allied with the United States and joined NATO (despite their distance from the North Atlantic).