Ignoring US warnings, President Erdogan says contracts for the advanced Russian missile defence system already signed.

Turkey will never turn back from a deal to buy S-400 missile defence systems from Russia, President Recep Tayyip Erdogan said, adding that Ankara may subsequently look into buying S-500 systems.

In an interview with broadcaster Kanal 24, Erdogan also said on Wednesday the United States should not try to discipline Turkey through trade measures, adding Ankara had its own penalties prepared.

“We concluded the S-400 issue, signed a deal with the Russians and will start co-production,” said Erdogan. “Later, we may work with S-500s,” the next generation system, he added.

The US has warned that procuring the S-400 systems from Russia could jeopardise defence industry deals between the NATO allies, and this week decided to end preferential trade with Turkey.

A State Department spokesman said on Tuesday that Ankara was told: “acquisition of the S-400 will result in a reassessment of Turkey’s participation in the F-35 programme, and risk other potential future arms transfers to Turkey.”

The US agreed to sell 100 of its latest fifth-generation F-35 stealth fighters to Turkey and has so far delivered two of the aircraft. But Congress last year ordered a delay in future deliveries.

NATO nations – particularly the US – view Turkey’s purchase of the Russian-made equipment with suspicion. Ankara says it needs alternative missile defences to counter regional threats.

Russia’s advanced S-500 anti-ballistic missile system will enter service with the Russian armed forces soon, Russian media reported last week.

The first group of military officers will complete a training course this year to use S-500, a long-range system that will form the backbone of Russia’s air and missile defence systems, TASS news agency said.