Turkey's Erdogan says S-400 deal 'nothing to do with US'

Turkey's purchase of the S-400 missile defence system from Russia has "nothing to do" with NATO or US security, Turkish President Recep Tayyip Erdogan said on Saturday.

"Everyone knows that this issue has nothing to do with neither NATO and F-35 project nor the security of the US," Erdogan said according to Turkey's state news agency Anadolu.

Turkey has faced repeated warnings from Washington that, if it purchases Russia's S-400 system, the US will cancel the sale of high-tech F-35 jets to Turkey.

"The issue is not about S-400. It is because Turkey takes action with its own will regarding the regional developments, particularly Syria," claimed Erdogan.

"It is clear why Turkey is buying this air defence system and how will it use it."

Top US military commander for Europe, General Curtis Scaparrotti, told the US Congress this week that NATO member Turkey should reconsider its plan to buy the S-400 from Russia or forfeit future American military aircraft and systems.

It was the latest in a series of warnings the US has made to Turkey over its plans to buy the S-400. The issue has aggravated already souring relations with Ankara, including tensions over the war in Syria.

US and NATO officials have repeatedly complained that the S-400 system can not be integrated into the NATO defence system. They have warned Ankara that Turkey risks both jeopardising its purchase of Lockheed Martin F-35 jets from the US and having sanctions imposed.

Some have said the US is concerned that the S-400 poses security risks to the F-35 Joint Strike Fighter project.

The US agreed to sell 100 of its F-35 fighters to Turkey in December and has so far delivered two of the aircraft. Deliveries were halted last year by Congress.

Turkey's bid to purchase the US Patriot missile system has also been hindered by its decision to buy the S-400 system.

"The S-400 is a done deal, there can be no turning back. We have reached an agreement with the Russians," Erdogan said in an interview with Kanal 24 on Wednesday.

"We will move toward a joint production. Perhaps after the S-400, we will go for the S-500."

Russia has utilised the S-400 system in its military operations in Syria. The missile system first made its way to the Hmeimim Air Base in Latakia after Ankara's military downed a Russian jet which it claimed entered Turkish airspace in 2015.

The countries have since become increasingly cooperative over Syria, where both are entangled in ongoing military operations and political negotiations to end the war.

The first S-400 system will be delivered to Turkey in July and become operational in October.