The move comes after US State Department said last week that President Donald Trump and Secretary of State Mike Pompeo “are examining all of the options in the CAATSA [Countering America's Adversaries Through Sanctions Act] legislation over Turkey’s purchase of Russian S-400 missile systems."

Ankara is set to retaliate against the sanctions that Washington intends to impose on Turkey over its purchase of Russia's S-400 air defence system, Turkish Foreign Minister Mevlut Cavusoglu said on Monday,

“If the United States slaps sanctions, we will respond in kind. A [relevant] step can also be taken with regard to the Incirlik airbase. This is a natural position under these circumstances, not a threat and blackmail,” Cavusoglu told Turkish news TV channel TGRT Haber.

Last year, Turkish Deputy Prime Minister Bekir Bozdag rejected media reports about US plans to withdraw its troops from the Incirlik air base in southern Turkey. This came after German troops left the base after German lawmakers were not allowed to visit the facility.

© AP Photo / Emrah Gurel Incirlik Air Base, on the outskirts of the city of Adana, southern Turkey (File)

Cavusoglu also suggested that US President Donald Trump is unwilling to slap sanctions on Ankara over its S-400 deal with Russia.

Cavusoglu added that the S-400 air defences will enter service at the start of 2020. He also pointed out that Turkey’s partners in the F-35 programme are concerned over Washington’s decision to suspend Ankara.

He made it clear that Turkey will “meet its needs elsewhere” if the US does not supply the F-35 fighter jets to Ankara.

The statement comes after the White House said last week that Turkey's move to buy Russian S-400 air defence systems “renders its continued involvement with the F-35[project] impossible”.

US Department of State spokesperson Morgan Ortagus said that President Donald Trump and Secretary of State Mike Pompeo are reviewing options in response to Turkey’s purchase of Russian S-400 air defence systems, including the imposition of sanctions as per CAATSA (Countering America's Adversaries Through Sanctions Act) legislation.

“As it relates to which sanctions options will be chosen, we don't preview the sanctions in advance, but I know that the Secretary [Pompeo] is obviously reviewing and working on this at present... They are in the process”, Ortagus added.

Earlier, the Turkish Defence Ministry had announced the beginning of S-400 deliveries to the country amid US claims that the missile system is incompatible with NATO's air defence weapons and may compromise the operations of the F-35 fighter jet.

© AP Photo / Turkish Defence Ministry Military vehicles and equipment, parts of the S-400 air defense systems, are unloaded from a Russian transport aircraft, at Murted military airport in Ankara, Turkey, Friday, July 12, 2019

Washington has repeatedly threatened to remove Turkey from the F-35 programme, warning that the US would no longer train Turkish pilots to operate the fifth-generation jet.

Turkish President Recep Tayyip Erdogan has repeatedly stressed that the S-400 agreement, signed by Moscow and Ankara in December 2017, is a “done deal.”