US lawmakers, including Democrats and Republicans have urged US President Joe Biden to not to sell F-16 fighter planes to Turkey saying they were confident that the US Congress would block any such exports.

In a letter to the US. President, and U.S. Secretary of State Antony Blinken, eleven members of the House of Representatives cited “a profound sense of concern” on recent media reports that Turkey may purchase forty new F-16s and 80 F-16 modernization kits.

“Following President (Tayyip) Erdogan’s September announcement that Turkey will purchase an additional tranche of Russian S-400 missile defense systems, we cannot afford to compromise our national security by sending U.S.-manufactured aircraft to a treaty ally which continues to behave like an adversary,” wrote the lawmakers.

The White House did not immediately respond to a request for comment.

A spokesperson for the State Department said, the department does not comment on correspondence with the US Congress.

Earlier this month, there have been media reports that Turkey had made a request to the United States to purchase 40 F-16 fighter jets and nearly 80 modernization kits for its existing fighters.

Previously, Turkey had ordered more than 100 Lockheed Martin F-35s, but after Ankara acquired Russia’s S-400 air defense system, Washington removed the NATO member from the program in 2019.

The letter was led by Republican Representative Nicole Malliotakis and Democratic Representative Carolyn Maloney.

“While we are confident that Congress will stand together to block any such exports should these plans progress, the United States cannot afford to transfer any advanced military equipment to the government of Turkey at this time,” reads the letter.

US-Turkey relations have gone through a turmoil in the past five years over disagreements on Syria and Ankara’s growing ties with Moscow, as well as its naval ambitions in the Mediterranean.