"As for the statements made by the US, this is the case of the presidents of two serious countries [Russia and Turkey] signing the agreement we are talking about. [S-400 and F-35] are two different things. We are partners with the US on the F-35 and we will continue our cooperation on both tracks. We are a sovereign state and we make decisions, which are in the best interests of our country,” Turkish Undersecretary for the Defense Industry Ismail Demir told Russian journalists on the sidelines of the Eurasia Airshow in Antalya.
He added that the agreement on the delivery of the S-400s from Russia was being implemented according to plan and that Turkey expects the first batch to arrive in July 2019.
In December 2017, Russian and Turkish representatives inked a loan agreement on the sale of the S-400 systems to Ankara.
According to the Turkish Defense Industry Secretariat, Ankara will buy two batteries of S-400 missiles, which will be manned by Turkish military personnel.
Washington is seriously concerned about Ankara's push to buy Russian S-400 systems.
In February, an unnamed US official told the Turkish newspaper Haberturk that this could "negatively influence the interoperability of NATO" and that the White House may introduce punitive measures in response.
"We want to help Turkey find a better alternative to meet its air defense needs," the official said.
The head of NATO’s cyber defense unit, Christian-Marc Liflander said that the S-400 system is not compatible with the air defense systems currently used by the alliance.
NATO has taken a more conciliatory approach however, with Secretary General Jens Stoltenberg reiterating the alliance's position regarding Turkey's purchase of S-400 missile defense systems, saying it is "a national decision."
READ MORE: US State Dept Warns Turkey of Possible Sanctions Over S-400 Purchase