Turkish F-35 pilots no longer flying at U.S. base - Pentagon

FILE PHOTO: A Lockheed Martin F-35 aircraft is seen at the ILA Air Show in Berlin, Germany, April 25, 2018. REUTERS/Axel Schmidt/File Photo

WASHINGTON (Reuters) - Training by Turkish pilots on F-35 fighter jets has come to a faster-than-expected halt at a U.S. air base in Arizona, U.S. officials said on Monday, as the United States winds down Ankara's involvement in the programme over Turkey's plans to buy a Russian air defence system.

The United States says Turkey's acquisition of Russia's S-400 air defences poses a threat to the Lockheed Martin Corp's F-35 stealthy fighters, which Turkey also plans to buy. Washington says Ankara cannot have both.