The US on December 14 imposed sanctions on Turkey’s military procurement agency after the NATO ally defiantly bought Russia’s S-400 air defence system.

US Secretary of State Mike Pompeo said in a statement: “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 defence and intelligence sectors.”

President Donald Trump’s administration said it was banning all US export licences to the Presidency of Defence Industries and refusing any visas for the agency’s president Ismail Demir.

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

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

Pompeo said: “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 defence sector, as well as Russian access to the Turkish armed forces and defence industry.

“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 defence requirements.”