Turkish President Recep Tayyip Erdogan said on Monday he had a constructive meeting with U.S. President Joe Biden on the sidelines of the NATO summit and has invited him to visit Turkey.
Biden said he had a heavy schedule but could pay a visit, according to Erdogan.
Erdogan signaled that the two leaders failed to find a way to overcome differences over Turkey's purchase of the S-400 advanced Russian missile defense systems. The U.S. says the technology is a threat to NATO and has removed Turkey from its F-35 fighter jet program.
"Our thoughts on the S-400 are the same as before, I relayed our same thoughts to Mr. Biden," Erdogan said.