NATO Secretary General Jens Stoltenberg said China is an emerging power, economically and militarily, and despite intelligence concerns, sees a "potential partnership between the two militaries", during an exclusive interview on FOX Business.
The US said on Monday it was halting all deliveries and joint work with Turkey on the F-35 fighter jet program if Ankara insisted on the deal.
"As Turkey's ally, we recognize Turkey lives in a tough neighborhood and its acquisition decisions are its sovereign choice", he added, while adding that the S-400 purchase was "fundamentally incompatible" with the Patriot offer. Russian Federation will deliver the first batch of the defence batteries in late 2019.
The US State Department said Pompeo had warned Ankara of "devastating consequences" if Turkey launches an offensive in Syria and urged the "swift resolution" of legal cases involving US citizens and US mission employees under investigation in Turkey.
The US has said Turkey's purchase of the Russian air defence system would compromise the security of F-35 aircraft, which are built by Lockheed Martin Corp and employ stealth technology.
Boeing to temporarily reduce 737 MAX production
The agency was also reluctant to ground the planes after the Ethiopian Airlines crash and was among the last agencies to do so. Boeing is cutting its 737 production rate as the company works to return the MAX airplanes to flight.
The S-400, they say, is created to detect and shoot down stealth fighters like the F-35. But he also floated the idea of creating a bilateral panel to try to quell United States fears that the system could give Russian Federation insights into Western weapons systems, including the F-35 fighter jet, for which Turkey builds the fuselage.
"Our alliance naturally requires that such statements are prepared with greater care, while avoiding to include matters that were not raised during meetings", he said.
The country came in for renewed criticism from the Trump administration on Wednesday when Vice President Mike Pence told an Atlantic Council forum marking the 70th anniversary of NATO in Washington D.C., "Germany still refuses to make the necessary investment of 2 per cent of its [gross domestic product] GDP to our common defence".
Pence threatened that if Turkey completes the purchase, Turkey will risk expulsion from the joint F-35 program.
Turkey's President Recep Tayyip Erdogan, left, in a first public appearance after Sunday elections in Istanbul, Thursday, April 4, 2019, listens as he visits an uncompleted museum dedicated to the July 15, 2015 coup attempt.
As Erdogan frenetically campaigned across Turkey in the lead-up to municipal elections held Sunday, she adds, "each and every rally he [brought] up S-400s, saying, "We're going to buy it, they told me not to buy it" - nearly making it look like it's a sign of his virility, his independence, his power on the world stage that he could say no to United States".
"Everybody believes the U.S.is no longer a balanced or objective" leader on the world stage, he said.