Turkey's decision to purchase Russia-made S-400 air defense systems is a "national decision," outgoing NATO Secretary General Jens Stoltenberg said September 14.
"It is a challenge and is well known that there is a disagreement between Turkey and especially the United States on this issue," Stoltenberg said at the conservative Heritage Foundation think tank in Washington DC, according to Hurriyet.
The NATO chief noted that, as far as his alliance is concerned, the only important thing is that "the different systems сan work together."
"Turkey is also important when it comes to dealing with the migrant and refugee crisis. They host millions of refugees, and they are important to implement the agreement between EU and Turkey on managing the flow of migrants on the Aegean sea," Stoltenburg said.
He also noted that Turkey has suffered, by a large number, the highest number of terrorist attacks, as well as a failed coup attempt.
"So, yes there is problem, there is a challenge, with the decision to buy S-400 combined with F-35. I welcome the dialogue that is addressed, but at the same time it's important to recognize the importance that Turkey is playing to the whole alliance," Stoltenburg added.
In July, the US Senate passed a bill restricting the sale of US-made F-35 stealth fighter jets to Turkey over Ankara's decision to buy the S-400 system. Opponents in the US of the S-400 deal argue that the purchase of a Russian-made anti-aircraft missile system will draw Turkey deeper into Moscow's growing sphere of influence in the Middle East.
According to a Washington Times report, the decision to buy Russian systems was made in part due to Ankara's frustration over Washington's backing of Kurdish militant groups battling Daesh in Syria.