ISTANBUL — Turkey's defense minister has reaffirmed the country's plans to use a Russian-made missile defense system it purchased despite continued objections from the United States.

Defense Minister Hulusi Akar told a parliamentary budget commission Thursday the military is continuing its checks and preparations of the S-400s as planned. 

Washington is strongly against NATO member Turkey's acquisition of the Russian anti-aircraft system and kicked Turkey out of its F-35 fighter jet program, saying the S-400s are a threat to the stealth fighter jets and wouldn't be interoperable with NATO systems.

Akar said Turkey is prepared to discuss with the U.S. its "anxiety" over the interoperability of the S-400s and the F-35s. "Our offer for a joint working group is still on the table," he said, in comments carried by the official Anadolu news agency. 

Turkey was making components for the F-35 and had planned to purchase 100 of the stealth fighters.

The U.S. has also warned Ankara that it risks U.S. sanctions under the Countering America's Adversaries Through Sanctions Act if the S-400 system is activated. President-elect Joe Biden is expected to take a tougher stance on the issue.

Turkey tested the missile defense system in October for the first time. The U.S. Department of Defense condemned the test "in the strongest possible terms."

Ankara argues it was forced to buy the Russian system because the U.S. refused to sell the American-made Patriot system. The Turkish government also points to what it considers a double standard, as NATO member Greece uses Russian-made missiles. 

"We will use the S-400 system in the same way that other NATO member states with existing S-300 systems use them within the NATO alliance," the defense minister said.