Turkey has decided to turn to Russia for defense system over its allies within NATO. It’s the latest sign that the relationship between NATO countries and Turkey remain strained. From Bloomberg:

Turkey has agreed to pay $2.5 billion to acquire Russia’s most advanced missile defense system, a senior Turkish official said, in a deal that signals a turn away from the NATO military alliance that has anchored Turkey to the West for more than six decades.

The preliminary agreement sees Turkey receiving two S-400 missile batteries from Russia within the next year, and then producing another two inside Turkey, according to the Turkish official, who asked not to be named because of the sensitivity of the matter. A spokesman for Russia’s arms-export company Rosoboronexport OJSC said he couldn’t immediately comment on details of a deal with Turkey.

Turkey has reached the point of an agreement on a missile defense system before, only to scupper the deal later amid protests and condemnation from NATO. Under pressure from the U.S., Turkey gave up an earlier plan to buy a similar missile-defense system from a state-run Chinese company, which had been sanctioned by the U.S. for alleged missile sales to Iran.

The missile deal with Russia “is a clear sign that Turkey is disappointed in the U.S. and Europe,” said Konstantin Makienko, an analyst at the Center for Analysis and Technology, a Moscow think-tank. “But until the advance is paid and the assembly begins, we can’t be sure of anything.”

The Russian system would not be compatible with other NATO defense systems, but also wouldn’t be subject to the same constraints imposed by the alliance, which prevents Turkey from deploying such systems on the Armenian border, Aegean coast or Greek border, the official said. The Russian deal would allow Turkey to deploy the missile defense systems anywhere in the country, the official said.