ANKARA, May 27. /TASS/. Russian technical specialists will pay a visit to Turkey to help putting Russian-made S-400 missile systems into operation, Turkish Minister of National Defence Hulusi Akar told the Haber Turk TV channel on Monday.

"The matter of the S-400 purchase is closed. It should be understood that it’s a done deal. Our president has repeatedly said that. Technical personnel will arrive from Russia to install the system," Akar said without giving the exact timeframe of the visit.

Speaking about the delivery of the Russian-made systems to his country, the defense minister said that "they may not be delivered in June, they are expected to arrive in the coming months."

When asked about Washington’s threats to renounce a deal with Turkey regarding the F-35 fifth-generation fighter jets if it purchases Russian missile systems, the minister replied: "if the United States changes its stance within the framework of the agreement, we will create our own world."

Akar also rejected media rumors about Washington’s demands to withdraw from the deal with Russia by the end of the first week of June.

"I have received no such information," he said.

Last week, CNN quoted sources at the Department of State as saying Turkey had a two-week deadline to make up its mind regarding the purchase of the US combat aircraft and Russia’s air defense systems. Washington demands Turkey sever the S-400 contract by the end of the first week of June or face negative consequences.

A group of US Congressmen, representing both the Democrats and the Republicans, on May 16 submitted for consideration of several committees of the US House of Representatives a resolution calling for sanctions against Ankara under CAATSA and also removing Turkey from the program on creating the advanced US fighter-bomber F-35 in case of the S-400 purchase.

The first reports about the talks between Russia and Turkey on the deliveries of S-400 air defense missile systems emerged in November 2016. Russia confirmed in September 2017 that the relevant contract had been signed. Akar earlier said that the deployment of S-400 surface-to-air missile systems would begin in October 2019. Rostec CEO Chemezov said in December 2017 that the S-400 deal was worth $2.5 billion.

The S-400 Triumf is the most advanced long-range air defense missile system that went into service in Russia in 2007. It is designed to destroy aircraft, cruise and ballistic missiles, including medium-range missiles, and can also be used against ground installations.

The S-400 can engage targets at a distance of 400 km and at an altitude of up to 30 km.