UPDATE 1-U.S. still pressing Turkey to 'walk away' from Russian missile purchase, official says

The United States is still in talks with Turkey to get Ankara to 'walk away' from the Russian missile defense system it bought, a senior State Department official said on Friday.

"There's still work to get the Turks to walk away from the S400s: be it turn it off, send it back, destroy it, what have you," the official told reporters, speaking on condition of anonymity. "That is still an ongoing issue. We're talking about re-mediating, re-addressing, reconciling. That's not off the table." Batteries of the S-400 began arriving in Turkey in July but have not yet been switched on, which the U.S. official acknowledged.

NATO allies Turkey and the United States have been at loggerheads over the purchase of the S-400 system, which the United States says is not compatible with NATO defenses and poses a threat to Lockheed Martin's F-35 'stealth' fighter jet. Washington has previously warned Ankara that it will face sanctions over the purchase and removed Turkey from its F-35 program but has fallen short of slapping such penalties.

The risk of sanctions under the Countering America's Adversaries Through Sanctions Act was part of a broader set of unresolved issues that the United States has with Turkey, the official said.

Also Read: Hope Turkey will 'act rationally' in terms of operation in northern Syria: Trump