WASHINGTON

Turkey's purchase of Russia’s S-400 missile defense system creates "unacceptable risks" for the U.S., a Department of Defense official said Thursday.

"The radar system would provide Russia with military sensitive info on the F-35, which is our top-quality fifth-generation aircraft," Andrew Winternitz, acting deputy assistant secretary of defense for European and NATO policy, said at a panel hosted by Foreign Policy magazine.

"From our perspective, there are no measures that can mitigate our concerns on this," he added.

Following protracted efforts to purchase an air defense system from the U.S. with no success, Ankara decided in 2017 to purchase Russia’s system.

American officials advised Turkey to buy the U.S. Patriot missile system rather than the S-400 system from Moscow, arguing it would be incompatible with NATO systems and expose the F-35 to possible Russian subterfuge.

Turkey, however, has emphasized that the S-400 would not be integrated into NATO operability and would therefore not pose a threat to the alliance.

Winternitz said the U.S. has been in constant contact with Turkey about the purchase and said the deal was incompatible with a 2016 NATO summit declaration that was signed by Turkey.

Despite this, he said Washington is "looking forward to a long continued bilateral relationship with Turkey".

"Our relationship is many layered, and this strategic partnership we have with them is going to remain, and we’re just hoping we can discuss this issue with them," he said.