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.
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).
From 1945 until 1991 Turkey was locked into a relationship with the United States. The United States was pursuing a strategy of containing the Soviet Union on a line running from Norway to Pakistan. Turkey was a key element because of its control of the Bosporus, but also because a pro-Soviet Turkey would open the door to direct Soviet pressure on Iran, Iraq and Syria. A Soviet-allied or Soviet-influenced Turkey would have broken the center of the American containment system, changing the balance of power. Along with Germany, Turkey was the pivot point of U.S. and NATO strategy.
From a Turkish point of view, there was no other option. The Soviets had emerged from World War II in an extremely powerful position. Western Europe was a shambles, China had become communist and the surplus military capability of the Soviets, in spite of the massive damage they had endured in the war, outstripped the ability of nations on their periphery -- including Turkey -- to resist. Given the importance of the Bosporus and Asia Minor to the Soviets, Turkey was of fundamental interest. Unable to deal with the Soviets alone, Turkey thus moved into an extremely tight, mutually beneficial relationship with the United States.
During the Cold War, Turkey was a strategic imperative of the United States. It faced the Soviets to the north and two Soviet clients, Syria and Iraq, to the south. Israel drew Syria away from Turkey. But this strategic logic dissolved in 1991 with the fall of the Soviet Union. By then, the union had fragmented. Russian power withdrew from the southern Caucasus and Balkans and uprisings in the northern Caucasus tied the Russian military down. Armenia, Georgia and Azerbaijan gained independence. Ukraine also became independent, making the status of the Russian Black Sea Fleet in Crimea unclear. For the first time since the early years of the Soviet Union, Turkey was freed from its fear of Russia. The defining element of Turkish foreign policy was gone, and with it, Turkish dependence on the United States.
It took a while for the Turks and Americans to recognize the shift. Strategic relationships tend to stay in place, as much from inertia as intention, after the strategic environment that formed them disappears; it often takes a new strategic reality to disturb them. Thus, Turkey's relationship with the United States remained intact for a time. Its ongoing attempts to enter the European Union continued. Its relationship with Israel remained intact even after the American rationale for sponsoring Turkish-Israeli strategic ties had diminished.