Turkey has received two additional S-400 air defense missile systems and more than 120 surface-to-air missiles from Russia, the TASS news agency reported Monday.

"Turkey has received two S-400 battalions, more than 120 surface [to] air missiles, as well as auxiliary equipment, spare parts and tools," a military diplomatic source told TASS.

The source added that the delivery and acceptance act was signed in Ankara in early December, starting a 20-month warranty maintenance period, TASS reported.

TASS said that Russia's state-run arms exporter refused to comment.

Ankara and Washington have been at loggerheads over Turkey's purchase of the S-400 systems, which the United States says are not compatible with NATO defenses and poses a threat to Lockheed Martin's F-35 'stealth' fighter jets.

The initial parts of the system were delivered to Ankara in July despite warnings about possible U.S. sanctions over the purchase. The United States has also expelled Turkey from the F-35 program but Ankara has so far dismissed the warnings. President Recep Tayyip Erdogan has said that the system would be fully deployed by April 2020.