Turkey, getting nervous about Iran's growing arsenal of ballistic missiles (not to mention the nuclear weapons program) is buying a billion dollars worth of American Patriot missiles. This will include the version that can intercept ballistic missiles (the PAC-3 anti-missile missile). Turkey wants to get at least a battalion of Patriots (13 launchers and three radar units.)
The U.S. Army has ten of its Patriot anti-aircraft missile battalions. Each battalion has 12-24 launchers (3-6 batteries). Each battery is manned by about a hundred troops, and contains a radar, plus four launchers. A battery can fire two types of Patriot missile. The $3.3 million PAC 3 missile is smaller than the anti-aircraft version (PAC 2), thus a Patriot launcher can hold sixteen PAC 3 missiles, versus four PAC 2s. A PAC 2 missile weighs about a ton, a PAC 3 weighs about a third of that. The PAC 3 has a shorter range (about 20 kilometers) versus 70 kilometers for the anti-aircraft version.
While each Patriot launcher, loaded with PAC 3 missiles, can only defend against ballistic missiles approaching within 20 kilometers, the Patriot radar can detect targets out to a hundred kilometers. Two PAC 3 missiles are fired at each incoming ballistic missile, to increase the probability of a hit. The PAC 3 missile has its own radar, and uses it to track the incoming warhead, and execute a collision course.
While both Turkey and Iran are Moslem countries, the two have been rivals for over a thousand years. Through most of that time, the Turks had the edge. The Iranians have not forgotten this, and any kind of payback would be widely popular in Iran. That would include Iran having a weapon they could threaten Turkey with, and that the Turks could not defend against. The Iranians would have to be careful with this sort of thing. The two countries share a border, and the Turks have a much more powerful army.