Nato member Turkey's plans to push forward with the acquisition of Russia’s S-400 advanced missile defence system are compete and final, Turkish President Recep Tayyip Erdogan said during a joint press conference with Russian President Vladimir Putin in Moscow on April 8, potentially setting up a final showdown with the US on the issue.

"We have already drawn up our road map regarding the S-400, and those who are calling on us to 'forgo' at this time clearly do not know us. If we have made an agreement, then the matter is over," Erdogan said following a session of the Russian-Turkish Cooperation Council in Moscow.

Last week, US Vice President Mike Pence became the latest Trump administration official to warn Ankara that the S-400 purchase was not acceptable.

The US and Nato have pointed out that it could be used to expose the performance data of the world’s most advanced jet fighter, the F-35, orders for which have been placed by Turkey. Should the Turks push ahead with purchasing the S-400, no F-35s will be delivered to them, the US has warned. Turkey would also most likely be expelled from the programme to manufacture and service the aircraft.

Syria efforts
Separately, at the press conference, the two leaders said they were continuing to coordinate efforts to stabilise the conflict in Syria.

“We are coordinating our efforts in the context of stepping up the intra-Syrian political process, particularly with an eye towards forming a constitutional committee as soon as possible,” Putin said.

Erdogan, moving on to bilateral trade potential, said Turkey aims at a $100bn trade volume with Russia and would set new targets for the near future, state-run Anadolu news agency reported.

“Notably, Russian-Turkish energy cooperation has become truly strategic,” Putin said in further remarks.

Russia is the largest natural gas supplier to Turkey. It exported 24bn cubic metres of gas to the country last year. This covers almost half of Turkey’s needs.