FILE PHOTO - U.S. soldiers stand next to the long-range air defence system Patriot during Toburq Legacy 2017 air defence exercise in the military airfield near Siauliai, Lithuania, July 20, 2017. REUTERS/Ints Kalnins

ANKARA (Reuters) - It is impossible for Turkey to accept the United States’ offer on purchasing Patriot defense systems as it currently stands, the chairman of Turkey’s Defence Industry Directorate said on Wednesday, adding that talks on the issue continued.

Speaking to broadcaster NTV, Ismail Demir also said two Lockheed Martin F-35 fighter jets would be delivered to Turkey next month.

U.S. officials have warned that Turkey’s purchase of Russian S-400 defense systems would jeopardize Ankara’s purchase of F-35 jets and possibly even result in U.S. sanctions. U.S. officials had set an informal deadline of Feb.15 for Ankara to respond to its rival offer on the Patriot systems purchases.