The Pentagon presented to Congress a report on the sale of one hundred F-35 fighters to Turkey, Reuters reported.

Turkey’s decision to purchase the Russian S-400 air defense missile systems has caused concern in the West, since Moscow could obtain data on the vulnerability of the most advanced US military aircraft, experts noted.

According to Pentagon’s chief arms buyer, Ellen Lord, Turkey’s plans to buy the S-400 system were “extremely problematical” and numerous US officials had discussed the issue with Ankara, but there were no signs that Turkey had changed its mind about buying the Russian system.

Some US lawmakers called for banning Turkey from selling fighters if it acquired the S-400, while the US does not exclude the imposition of sanctions in this case.