In an exclusive interview with Sputnik on Thursday, NATO Secretary-General Stoltenberg said Turkey was free to buy any kind of equipment, including Russian S-400 air defence missile systems.
Commenting on reports on Turkey's purchase of Russia's S-400 air defence missile systems, Stoltenberg said that each NATO member state makes its own decision on the purchase of weapons.
"It's up to each and every individual ally to decide what kind of equipment they acquire. This is a national Turkish decision. What is important for NATO is that our different systems are working together, that we have what we call interoperability. For this system, there has been no request for integrating it into the NATO air defence system. So that has not been on the table," Stoltenberg said.
"They went crazy because we made the S-400 agreement. What were we supposed to do, wait for you? We are taking and will take all our measures on the security front," Erdoğan said on Wednesday.
Turkey has agreed to pay Russia $2.5 billion for the S-400 systems, a Turkish official said on July 13.
'TURKEY'S PURCHASE OF S-400 NOT ALTERNATIVE TO NATO'
The contract Ankara signed with Moscow on the purchase of S-400 air defence missile systems is not an alternative to Turkey's NATO membership, Turkish presidential spokesman Ibrahim Kalın said Thursday.
"We are developing good cooperation with Russia, but this is not an alternative to our relations with the West and NATO. On the contrary, they complement each other," Kalın told reporters.