Turkey says it has finalized a deal to buy Russia's advanced S-400 missile-defense system.

NATO leaders appear to be sending warnings to Turkey over the purchase and potential deployment of the weapon system.

Throughout the summer and fall, Turkey moved ahead with plans to buy Russia's advanced S-400 anti-missile defense system.

The rest is just details now," Turkish Defense Minister Nurettin Canikli said this weekend.

As a NATO member, Turkey would typically buy weapons interoperable with the defense alliance's weapons systems, but Ankara sought out new options after several NATO countries declined to renew their deployments of Patriot missile-defense systems in Turkey, leaving only a handful there.

He has also expressed frustration with the EU over its response to the attempted coup against him in summer 2016 and accused the bloc of "messing us about" on issues like visas and Syria migrants.

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