U.S. Secretary of State Mike Pompeo has warned his Turkish counterpart against purchasing a Russian surface-to-air missile system.
Meeting on the sidelines of a NATO gathering on April 27, Pompeo told Turkish Foreign Minister Mevlut Cavusoglu that the S-400 system, radars, and missile batteries will not be integrated with those of Ankara’s NATO allies, a senior U.S. official said.
"The secretary underscored the seriousness of U.S. concerns...if [the Turkish authorities] go ahead," the official said in a briefing with reporters in Brussels.
"He asked Cavusoglu to closely consider NATO interoperable systems," the official added.
The State Department official said Pompeo reminded his Turkish counterpart that Ankara could face sanctions if it went through with the S-400 purchase.
Turkish defense officials say Ankara and Moscow have signed a deal under which Russia will supply up to two S-400 surface-to-air missile batteries to Turkey.
Turkey's Undersecretariat for Defense Industries (SSM) said in December that delivery of the initial battery of the air-defense system is planned for the first quarter of 2020.
The deal, reportedly worth about $2.5 billion, has caused concern in the West because Turkey is a member of NATO and the antiaircraft systems cannot be integrated into the alliance’s defenses.
Turkey's move to acquire the missiles has been regarded in some Western capitals as a snub to NATO amid tensions with Russia over its role in the wars in Syria and eastern Ukraine.