Turkey's defense ministry had earlier said that the first parts of the S-400 defense system were delivered to Ankara on Friday.
The S-400 Triumph, which became operational in 2007, is created to destroy aircraft, cruise and ballistic missiles, including medium-range ones. Officials told Turkey if the S-400 purchase went through the country would be barred from the F-35 program.
An S-400 being unloaded in Turkey. A defense official told reporters that Acting Secretary of Defense Mark Esper spoke with his Turkish counterpart for half an hour during the afternoon, but said there will be no readout from the call.
Erdogan confirmed on Monday that preparations for the shipment of the weapons system were underway, and said on Wednesday that Turkey would use the system "wherever and however we need them".
Although expressed sympathy toward Turkey's decision to purchase the Russian system during a meeting with Turkish President Recep Tayyip Erdogan on the sidelines of a meeting in Japan, Washington has repeatedly said that the Russian system is incompatible with North Atlantic Treaty Organisation systems and is a threat to the F-35. Last month, the two presidents met in Japan on the sidelines of the G-20 summit of the world's largest economies. US officials fear that if Turkey has both the F-35 and Russia's most advanced air defense system in its hands, then Russians may gain access to F-35 technology and later target its weaknesses.
The Senate Armed Services and Foreign Relations Committees issued a joint statement following the news that Turkey had taken delivery of the S-400. "So he buys the other missile and then, all of a sudden, they say, 'Well, you can now buy our missile.' You can't do business that way". "And I don't think he was treated fairly".
The first parts of the Russian missile system arrived on three planes at Ankara's Murted air base, Turkish media reported.
Even though delivery of the S-400 has begun, there could be potential wiggle room to avert a full-blown crisis.
Twenty Turkish servicemen received training from Russian Federation in May-June and 80 more Turkish servicemen will receive training to use the S-400 system, the source was quoted as saying.
Turkey has given mixed messages over the timing of the activation of the missile system. "We have heard from him personally that this would not happen", Erdogan said.
Turkey has refused to bow to US pressure, insisting that choosing which defense equipment to purchase is a matter of national sovereignty.
Turkish officials argue Turkey is in a tough neighborhood, bordering Iran, Iraq, and Syria.
U.S. officials have since encouraged Turkey to buy the Patriot missile defence system instead of the S-400s.
"From a military perspective there is no logic", said retired general Haldun Solmazturk, who now heads the Ankara-based 21st Century Institute research institution. The Trump administration must now decide to what extent it will follow through on its own laws and policies to punish Turkey.
He added that Ankara "continued to look into the feasibility of purchasing US Patriot missile systems".
Global relations professor Huseyin Bagci of Ankara's Middle East Technical University said Turkey "feels more and more alone in the Western world" without direct support from any of these countries.
The United States and North Atlantic Treaty Organisation have opposed the deal, saying the system is not compatible with NATO's defense network and may expose the F-35 to possible Russian interference. And the Americans have made a lot of mistakes.
Last month, Erdogan urged the United States to not let the purchase of the S-400 deteriorate strong ties between the two countries.
This looks set to prompt a major rift between Washington and one of its key North Atlantic Treaty Organisation allies. Ozel, for one, warns that any break between Ankara and the alliance will have serious consequences. "We are strategic partners with the United States". "It started in 1947. -Turkish trade and defense cooperation", he told JNS.
"We say this each time".