The United States has decided to stop accepting any additional Turkish pilots who planned to come to the United States to train on F-35 fighter jets, U.S. officials say, in a clear sign of the escalating dispute over Ankara's plans to purchase Russian air defenses.
The two NATO allies have sparred publicly for months over Turkey's order for Russia's S-400 air defense system, which Washington says poses a threat to the Lockheed Martin Corp F-35 stealthy fighters, which Turkey also plans to buy, Reuters reported.
The United States says Turkey cannot have both, but has avoided taking steps until now to curtail or halt planned training of Turkish pilots in the program, a reprisal that could be seen as an embarrassment in Turkey.
The two U.S. officials, who spoke to Reuters this week on condition of anonymity, left open the possibility the decision could be reversed, perhaps if Turkey altered its plans. They said the decision so far only applied to upcoming rounds of Turkish pilots and maintenance crews who would have normally come to the United States.
There has not yet been a formal decision to halt the training of the Turkish pilots and maintenance crews now at Luke Air Force Base in Arizona, the sources said. Still, Reuters reported last week that the step was being seriously considered.
Four Turkish pilots are currently training at Luke. Two additional Turkish pilots are at the U.S. base working as instructors. Beyond those six Turkish officers, there are an additional 20 Turkish aircraft maintainers at the base undergoing training as well, the U.S. military says.
If Turkey were removed from the F-35 program, it would be one of the most significant ruptures in recent history in the relationship between the two allies, experts said.
The disclosure of the decision on the pilots follows signs that Turkey is moving ahead with the S-400 purchase. Defense Minister Hulusi Akar said on May 22 that Turkish military personnel were receiving training in Russia to use the S-400, and that Russian personnel may come to Turkey.
President Tayyip Erdogan said on Tuesday it was "out of the question" for Turkey to back away from its deal with Moscow.
The Pentagon declined comment on whether it would accept new Turkish pilots.