Earlier this month, Erdogan said Turkey had also been discussing a U.S. offer to sell Patriot missiles. "I hope these systems will be delivered to our country next month", Erdogan said.
Mr Erdogan said he hoped to resolve the situation with the United States through phone diplomacy ahead of a meeting with President Trump at the end of June, Reuters reported.
USA officials had wanted Turkey to buy its Patriot missile system instead.
The purchase has raised eyebrows among Turkey's North Atlantic Treaty Organisation allies and provoked anger in Washington, which expected Ankara to opt for the American Patriot air defence system instead.
"We do not want to have the F-35 in close proximity to the S-400 over a period of time because of the ability to understand the profile of the F-35 on that particular piece of equipment", she said.
Following protracted efforts to purchase an air defense system from the USA with no success, Ankara decided in 2017 to purchase the Russian S-400 system.More news: Ubisoft shows off Watch Dogs: Legion
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Ankara also plans to buy 100 of the jets for its own military's use.
He noted that Ankara and Moscow had signed the deal with a pledge for a reasonable price and future joint production.
"This is not an attack system but a defence system". The Nato allies have sparred publicly for months over Turkey's purchase of the S-400s, which Washington has said could trigger United States sanctions. "Won't we take necessary measures to defend our country?" he said.
"We reject the wording [of] the letter [by acting Defense Secretary Patrick Shanahan] to our defense minister".
The Russian military said late on Wednesday that Moscow and Ankara had struck a deal for a complete cease-fire in the northwestern province of Idlib, the last stronghold of Syria's rebellion. Ankara has proposed that the two allies form a working group to assess the impact but says it has yet to hear back from Washington.
Erdogan also discussed the situation at Turkey's border with Syria, pledging to sweep the YPG Kurdish militia from northern Syria, and east of the Euphrates, revitalizing a plan put on hold after the United States said it would pull its troops out of the area.