The day before, President Recep Erdogan announced that Ankara would purchase an additional batch of S-400 air defense systems from Moscow.

A group of congressmen from both parties called on the administration of President Joe Biden not to sell F-16 fighter jets to Turkey and said that Congress would block any attempt to implement such a deal.

In a written appeal to Joe Biden and Secretary of State Antony Blinken, 11 lawmakers expressed “deep concern” about recent reports that Turkey may purchase 40 new F-16 fighter jets manufactured by Lockheed Martin from the United States and 80 kits for upgrading the F-16.

The letter, dated October 25, was at the disposal of Reuters on Tuesday.

“After President Erdogan announced in September that Turkey would acquire an additional batch of Russian S-400 missile defense systems, we cannot afford to jeopardize our national security by sending American-made aircraft to an alliance ally that continues to behave like our opponent,” the appeal says.

The White House and the Department of State have not yet responded to Reuters’ request for comment.

Earlier this month, Reuters reported that Turkey had asked the United States to purchase 40 Lockheed Martin-made F-16 fighter jets and almost 80 kits for upgrading the F-16 fighter jets that Turkey already has.

Ankara has also previously ordered more than a hundred F-35 bombers, also produced by Lockheed Martin. Still, the United States excluded Turkey from the F-35 program in 2019 after Ankara acquired Russian S-400 air defense systems.

The initiators of the appeal were Congresswoman Nicole Malliotakis, representing the Republican Party, and Democrat Carolyn Maloney.

“While we are confident that Congress will unite to block any such export deal if these plans are implemented, the United States cannot currently afford to transfer modern military equipment to the Turkish government,” the letter says.

The partnership between the United States and Turkey, NATO allies, has seriously weakened over the past five years due to disagreements over Syria, the strengthening of Ankara’s ties with Moscow, its naval ambitions in the Mediterranean region, and the infringement of rights and freedoms in Turkey.