Turkey is set to test its new Russian S-400 missile defences on Monday despite Washington’s opposition, Turkish media reported.

Turkish F-16 warplanes will reportedly fly over the capital Ankara on Monday and Tuesday to test the new systems which have strained relations between the two NATO allies Turkey and the United States.

Turkey received the second shipment of a battery for the Russian S-400 missile defence system in September and said that it would be active in April 2020.

The first delivery was completed in July, leading to a decision by Washington to cancel its F-35 fighter jet sales to Turkey over the purchase.

The US administration says Turkey’s purchase of the Russian S-400 missile system could allow Moscow to obtain intelligence on US-made F-35 jets.

Washington expelled Ankara from the F-35 programme as a result, but it says the NATO ally can get back in if it pledges to never activate the missiles and refrains from buying from Russia in the future.

Otherwise, it says it must impose sanctions on Turkey under 2017’s Countering America’s Adversaries Through Sanctions Act (CAATSA).

Turkey believes its S-400 purchase is not sanctionable under US law because the sale was sealed before Congress passed the sanctions bill against Russia.

Ankara also rejects concerns that the S-400s could spy on the next-generation F-35 fighter jet and complains that its suspension from the F-35 programme is unwarranted.

Turkish President Recep Tayyip Erdogan proposes forming a joint commission to resolve the issue and would still like to purchase US-made Patriot missiles if terms can be agreed.

Trump's terms

Prior to their latest White House meeting, Middle East Eye revealed that US President Donald Trump warned Erdogan in a letter that he would soon have to impose sanctions on Turkey over its purchase of the Russian systems if Ankara did not accept his proposed terms.

According to MEE's sources, Trump also said that Turkey could be readmitted into a partner programme for the US's next-generation F-35 fighter jet if it agreed not to activate the S-400 systems and committed to not purchasing Russian weapons systems in the future.

A senior State Department official told reporters last week that Turkey needed to "get rid of" the Russian system.

The comments came after Erdogan met Trump at the White House on 13 November.

Following the meeting, Trump called the Turkish acquisition of the S-400 missiles a “very serious challenge” to bilateral relations, but he described his meeting with Erdogan as “wonderful”.

Meanwhile, Erdogan told reporters that Turkey cannot risk its relationship with Russia.

As recent relations between Ankara and Moscow have strengthened, Kremlin spokesman Dmitry Peskov announced on Monday that Russian President Vladimir Putin will visit Turkey in the first week of January to take part in the gas pipeline "Turk Stream" launch ceremony.