The U.S. Air Force has stopped ongoing training Turkish pilots on the F-35 advanced fighter jets before an end date for "safety" concerns, the Pentagon said Tuesday.
"The department is aware that the Turkish pilots at Luke AFB [Air Force Base] are not flying," agency spokesman Lt. Col. Mike Andrews said in a statement. "Without a change in Turkish policy, we will continue to work closely with our Turkish ally on winding down their participation in the F-35 program."
But CNN reported the decision was made "despite there being no evidence the Turks pose a threat to the aircraft or US personnel or would be unable to concentrate on flying."
The actions are the latest in a set of moves by the U.S. to try to remove Turkey from the F-35 program amid a standoff with its NATO ally over the purchase of Russian S-400 missile defense system.
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.
U.S. officials argued it would be incompatible with NATO systems and expose the F-35 to possible Russian subterfuge, but Turkey has emphasized the S-400 would not be integrated into NATO operability and would not pose a threat to the alliance.
Ankara said it was Washington's initial refusal to sell its Patriot missile system that led it to seek other offers, adding that Russia offered a better deal that included technology transfers.
Acting Secretary of Defense Patrick Shanahan said last week in a letter to his Turkish counterpart the F-35 program for Turkish pilots would end July 31st and halted any new Turkish pilots from enrolling, giving pilots enough time to complete their training. However, this action would cut short their trainings.
The decision was made as an "operational pause" by the wing commander at Luke Air Force Base Brig. Gen. Todd Canterbury last Friday.
"The commander was focused on safety, which is what we rely on commanders to do. There was no intent to counter Acting Secretary Shanahan's letter to Minister [Hulusi] Akar or intent," a defense official said on the condition of anonymity.