But Turkish President Recep Tayyip Erdogan has refused to back down and said he is confident Turkey will not face U.S. sanctions.
The purchase has become a bone of contention between North Atlantic Treaty Organisation allies, Ankara and Washington, with The White House strongly opposed to the system's use in North Atlantic Treaty Organisation airspace citing practical and security concerns.
The United States has said that if fellow North Atlantic Treaty Organisation member Turkey does not cancel the S-400 deal by July 31, Ankara will be blocked from purchasing the next-generation F-35 fighter jets.
While there's no immediate reaction from the Trump administration, the development is likely to trigger sanctions from the United States.
"We invite the USA side to avoid taking wrong steps, excluding diplomacy and dialogue, that will harm relations", spokesman Hami Aksoy said, adding Ankara had still not received a response to its proposal to set up a working group to look into the impact of the S-400 purchase.
These range from banning visas and denying access to the US -based Export-Import Bank, to the harsher options of blocking transactions with the USA financial system and denying export licenses.
North Atlantic Treaty Organisation has yet to react officially to the Turkish announcement, but an alliance official speaking on condition of anonymity told the AFP news agency that the 29-member bloc is "concerned about the potential consequences" of the purchase.
The directorate added that the delivery would continue in the coming days. 'Once the system is completely ready, it will begin to be used in a way determined by the relevant authorities'.
Investors in Turkey have been concerned about the impact of potential U.S. sanctions on an economy that fell into recession after a currency crisis a year ago. The decision followed assertions from Erdogan that "there can be no turning back" on the deal.
Russian Federation began the delivery of an advanced missile defence system to Turkey it has been reported, a move likely to trigger USA sanctions against a North Atlantic Treaty Organisation ally and drive a wedge into the heart of the military alliance.
"It's a complicated deal". "In the event of any issues, we immediately work the phones".
"If Congress says CAATSA takes effect, can Trump really say, 'I will not be implementing it?' He can, but can he get away with it?"
According to US Treasury regulations, passed under Obama, the White House must impose at least five out of 12 available sanctions against any party engaging in a "significant transaction" with the defense sector of the Russian government. When Turkey released North Carolina pastor Andrew Brunson from detention in October, the president tweeted he was looking forward to "good, perhaps great, relations between the United States & Turkey".
Soner Cagaptay, director of the Turkish Research Program at The Washington Institute, said Turkey's purchase of the Russian system marks a "tectonic" shift in Turkey's security and foreign policy.
A Turkish Defense Ministry video showed two planes landing at the air base and unloading various military trucks, some of which appeared to be carrying parts of the system.
Experts and analysts now question whether the US can continue to rely on Turkey.
"We are aware of Turkey taking delivery of the S-400". USA 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.