Anxieties have emerged among Turkish MPs that the US Congress may condition the sale of F-35 warplanes to Turkey on Ankara cancelling its deal with Russia to buy the advanced S-400 missile defence system.

Turkish lawmaker Volkan Bozkir, who headed a Turkish parliamentary delegation to Washington last week, was on March 27 cited by Hurriyet as relaying such concerns. Turkey has ordered 100 F-35s in a transaction that would award Turkish companies participation in the production and maintenance of the new stealth multirole fighters.

Relations between Washington and Ankara are on tenterhooks over a range of issues including the new closeness that Nato member Turkey has developed with Moscow in the past year. The fact that Turkey did not join in with the wave of expulsions of Russian diplomats around the world in response to the Skripal nerve-agent poisoning affair in the UK will not have eased tensions in the relationship.

“Senators did not tell us this [about the conditioning of the F-35 deal], but when we spoke to their advisers this was the message that emerged,” Hurriyet quoted Bozkir, a member of Turkey’s ruling AK Party, as saying.

Turkey’s Defence Minister Nurettin Canikli, however, denied any link between Turkey’s purchase of the Russian S-400—which is incompatible with systems used by other Nato countries—and American jets. “Turkey joined the F-35 project years ago and deliveries will start from next year,” he said. Canikli added: “First of all this is a commercial activity, agreements have been made and Turkey has fulfilled its responsibilities under those agreements. We’ve made payments and all sides will fulfill their responsibilities.”

The UK, Italy, Australia, Canada, Norway, Denmark, the Netherlands, and Turkey are all part of the active development program for the F-35 Lightning II, manufactured by Lockheed Martin. It amounts to the most expensive military weapons system in history.

As for the course of bilateral relations between the US and Turkey, it is noteworthy that Turkish officials have made few comments about the Skripal poisoning and allegations that Russia was behind the attempted murder of the former Russian spy and his daughter in the city of Salisbury, but on March 26 Turkish Foreign Ministry spokesperson Hami Aksoy stated: “Turkey acknowledges the use of chemical weapons as a crime against humanity, and sees the attack in England on these terms and condemns it.”

Aksoy's statement pointedly made no mention of any possible role played by Russia in the nerve-agent attack, and on the same day that he spoke Turkish deputy prime Minister and government spokesperson Bekir Bozdag remarked: “Turkey sets its foreign policy on the basis of Turkish national and state interests. Right now Turkey and Russia have a positive relationship, so we will not be making any kind of decision on Russia.”

On March 28, Nato said it had decided to expel seven Russian diplomats in response to the Skripal affair. The US is evicting 60 and, worldwide, in excess of 100 are to be sent packing by more than 20 countries in a show of solidarity against Russian aggression. There was never any question, however, that Turkey would join Nato and its Nato allies in responding in such a fashion.