Turkey, unlike its NATO allies, is increasing its defense spending. Currently, Turkey spends 1.8 percent of its GDP on defense, versus an average of 1.6 percent for all NATO members. France, Britain, Poland, Bulgaria and Greece all spend between 2-2.6 percent.
Turkey has to spend more for several reasons, one of them being they still have a large military. There are 400,000 active-duty personnel and 200,000 reservists. There is also a paramilitary national police force of 180,000 personnel and 50,000 reservists. This force has some armored vehicles and helicopters.
But even at the end of the Cold War, many of their weapons and much of their equipment was old, and a lot of the current and future spending is for buying replacement gear. This includes a new tank (based on a South Korean design) built in Turkey. Then there are the new F-35 stealth aircraft, up to a hundred of them. There are also upgrades for 200 older F-16s. Warships need to be replaced or upgraded.
The Turks are not doing all this to invade anyone. They have no intention of restoring the old Ottoman Empire (that dissolved in 1918), but they do need a large force to survive in what is a rough neighborhood. Their Arab neighbors (Syria and Iraq) are violent and unpredictable. But the Arabs also fear the Turks, and the Turks feel safer by keeping it that way. Iran is an ancient enemy. Their Christian neighbors (Georgia, Armenia, Bulgaria and Greece) are easier to get along with, except for the Greeks. Most of Turkey's neighbors are also building up their armed forces, usually (except in the case of Greece) for reasons that have little or nothing to do with Turkey.
Until the end of the Cold War, the Turkish armed forces were responsible for defending NATO's southern flank. But Turkey has not been at war since the 1920s. There have been some minor skirmishes with the Greeks, and two decades of irregular war with their Kurdish minority. There has also been some peacekeeping, and participation in the Korean War (with a brigade). The Turks made a reputation for themselves in Korea, and their campaigns against the Kurdish rebels has shown that Turkish troops are still very effective. The Turks see that warrior reputation as their most powerful defense, but modern weapons make it even more convincing.
The most worrisome recent development in Turkey is the return of religion. An Islamic party, dedicated to honest government and more religion in general, has been running the country for most of the last decade. The Turkish ruling class largely discarded Islam as a factor in government, and public life, in the 1920s and 30s. But most Turks clung to ancient religious, and cultural traditions. The continued corruption in the government, and in society in general, was not only a drag on economic progress, but also immensely unpopular. What is uncertain is whether the use of religion to battle moral deficiencies will have ugly side effects.