U.S. President Donald Trump has the authority to waive sanctions on Turkey for its purchase of Russian air defense systems and should find a "middle ground" in the dispute, President Recep Tayyip Erdogan said on Sunday.

Erdogan's comments came two days after NATO member Turkey took delivery of the first consignment of advanced Russian S-400 missile defense system parts, despite warnings from Washington that the move would trigger U.S. sanctions.

Broadcaster Haberturk quoted Erdogan as telling Turkish journalists that Trump "has the authority to waive or postpone CAATSA," referring to U.S. sanctions designed to prevent countries buying military equipment from Russia.