The United States on Monday imposed sanctions on Turkey's military procurement agency after the NATO ally defiantly bought Russia's S-400 air defense system.

"Today's action sends a clear signal that the United States will fully implement (US law) and will not tolerate significant transactions with Russia's defense and intelligence sectors," Secretary of State Mike Pompeo said in a statement.

President Donald Trump's administration said it was banning all US export licenses to the Presidency of Defense Industries and refusing any visas for the agency's president, Ismail Demir.

Russia last year delivered the S-400 air defense system despite warnings that it is not compatible with being part of the NATO alliance.

A rocket launches from a S-400 missile system, a version of which was purchased by Turkey in defiance of its NATO allies, in September 2020 at Russia's Ashuluk military base
A rocket launches from a S-400 missile system, a version of which was purchased by Turkey in defiance of its NATO allies, in September 2020 at Russia's Ashuluk military base AFP / Dimitar DILKOFF

Turkish President Recep Tayyip Erdogan had warned that sanctions would be "disrespectful," although his government went ahead with testing.

"The United States made clear to Turkey at the highest levels and on numerous occasions that its purchase of the S-400 system would endanger the security of US military technology and personnel and provide substantial funds to Russia's defense sector, as well as Russian access to the Turkish armed forces and defense industry," Pompeo said.

"Turkey nevertheless decided to move ahead with the procurement and testing of the S-400, despite the availability of alternative, NATO-interoperable systems to meet its defense requirements."

The United States already evicted Turkey from joint efforts in developing the F-35 fighter-jet.

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