"The S-400 deal is a done deal and we will not step back from this," he told a think-tank forum in Washington, where he is taking part in 70th anniversary celebrations of NATO.

The United States said Monday that it was halting shipment of F-35 parts of Turkey as well as joint manufacturing work due to Ankara's purchase of the S-400 missile defense system from Russia.

Cavusoglu said Turkey turned to Russia as it could not buy US Patriot missiles and quoted President Donald Trump as saying in an unspecified phone call that his predecessor Barack Obama had made a "mistake" not to sell the system to Ankara.

However, the Trump administration has since made clear that it is ready to sell Patriot missiles to Turkey -- if it drops the S-400 system.

The Turkish foreign minister said the S-400 deal did not signal a warming toward Russia.

"We disagree with Russia on many issues," Cavusoglu said, pointing to Moscow's "aggression" in the Black Sea and pledging never to recognize Russia's annexation of the Crimean peninsula from Ukraine.

"We have been working with Russia," he said.

"But it doesn't mean that we are undermining the alliance and we agree with Russia on everything. There is no shift on our foreign policy."

US policymakers worry that Russia will obtain data from the F-35s to hone the ability of the S-400 to shoot down Western planes.

Cavusoglu said the S-400 system would be separate from NATO infrastructure in Turkey with no linkages to the F-35s.