Earlier, Washington reportedly gave Ankara until the end of the first week of June to either scrap the S-400 deal with Russia or face penalties, which would include sanctions and the cancelling of the delivery of 100 F-35 jets.

Turkey buying Russia’s S-400 missile systems could contribute to Moscow’s alleged push to disrupt NATO, US’ NATO ambassador Kay Bailey Hutchison, told the US broadcaster CNBC.

Accusing Russia of continuing “to probe ways” to weaken the alliance, Hutchison also warned that it’s unacceptable to place the S-400 under the same military control as US F-35 fighter jets.

READ MORE: 'Very Negative' Consequences For Turkey If S-400 Deal Takes Place — State Dept

Turkey may “lose association” with the F-35s that they have already ordered, she said, adding, “you have to make a choice; you can have one or the other but not both.”

Her remarks come after US Acting Assistant Secretary of Defence for International Security Affairs Kathryn Wheelbarger told the Atlantic Council in Washington in late May that Turkey’s deployment of the S-400 systems would be “devastating” for the US F-35 fighter programme.

Also, it would potentially “rupture Turkish inter-operability with NATO, a key aspect of the defence of the Alliance, and let’s be clear — the S-400 is a Russian system designed to shoot down aircraft like the F-35. And it is inconceivable to imagine Russia not taking advantage of that collection opportunity”, Wheelbarger claimed.

READ MORE: Ankara Ready to Receive Russian-Made S-400 'Any Moment' — Foreign Minister

Turkish Ambassador to the US Serdar Kilic, for his part, said that US F-35 fighter jets would not be in the coverage area of the S-400 systems deployed to Ankara.

The Russian President’s spokesman Dmitry Peskov in turn stressed that Moscow has “an extremely negative” stand on Washington's calls on Turkey to abandon the deal on buying Russian S-400 systems.

“We believe that such ultimatums are inadmissible”, Peskov told reporters, when asked about the Kremlin's stand on such statements.

His comments followed the CNBC saying, citing sources, that the US has given Turkey two weeks to cancel its S-400 deal with Russia. Otherwise, Washington will reportedly slap sanctions on Turkey or remove Ankara from the Lockheed Martin's F-35 programme.

READ MORE: Erdogan Vows to Further Boost Turkey's Security With S-400 Despite Spat With US

Ankara underscored that the purchase of military equipment is its sovereign affair and ruled out the possibility of abandoning its S-400-related plans.Moscow and Ankara inked a $2.5 billion agreement for the delivery of four S-400 batteries to Turkey in late 2017. The first of the missile systems are expected to be delivered in July.

Ankara has repeatedly emphasised that its commitment to the S-400 deal is non-negotiable, and has insisted that the batteries are not a threat to NATO, the US or the F-35 in any way. Turkish President Recep Tayyip Erdogan in turn earlier called Ankara’s purchase of the S-400 a “done deal” and a “matter of national sovereignty”.