A Turkish defense official quickly cast doubt on reports that Russia and Türkiye signed a contract to ship Ankara a second batch of S-400 air defense systems after Russian-state news agency TASS broke the news Tuesday, citing the head of Russia's military cooperation service.

TASS cited the head of Russia’s military cooperation service, Dmitry Shugayev, as saying: "I want to note that the relevant contract has already been signed. It envisions the localization of production of certain components of the system."

Türkiye’s initial 2020 purchase of the Russian S-400 system angered the United States, a NATO ally, which imposed sanctions on Türkiye in retaliation.

A Turkish defense official said on Tuesday there were "no new agreements."

"The original contract that was signed with Russia for the purchase of S-400s already included two batches. The purchase of a second batch was included in the original plan and the related contract," the official said.

"Therefore, we do not have any concrete developments worth reporting. The process is ongoing and there are no new agreements."

Any new defense contract between Russia and Türkiye would provoke serious concern from Washington at a time when it is trying to isolate Russia and maintain NATO unity in the face of Russia’s invasion of Ukraine.

Türkiye has not joined in on Western sanctions against Russia but has been active in mediation efforts since Russia invaded Ukraine in February. It was instrumental in brokering an agreement last month to enable a resumption of Ukrainian grain exports via the Black Sea.

Türkiye and Russia signed a first accord in December 2017 on deliveries of Russian S-400 surface-to-air missile batteries, reportedly worth around $2.5 billion. Türkiye received the first deliveries in July 2019.

The U.S. response to the purchase was to unilaterally expel the NATO ally Türkiye from the F-35 fighter jet development program, where it was a major manufacturer and buyer.

Türkiye has called the move unjust and demanded reimbursement for its $1.4 billion payment.

Washington argues that the S-400s could be used by Russia to covertly obtain classified details on the F-35 jets and that they are incompatible with NATO systems.

Türkiye, however, insists that the S-400 would not be integrated into NATO systems and would not pose a threat to the alliance.

Washington later also sanctioned Turkish defense industry officials, including İsmail Demir, head of the Presidency of Defense Industries (SSB), while U.S. senators have from time to time said the country may face more sanctions if it continues to purchase the Russian system.

Ankara says it acquired the system after the U.S. refused to sell it Patriots in the first place.