US President Donald Trump expressed concern about the procurement by Ankara of Russian S-400s and called for cooperation with Washington to strengthen NATO, CNBC reported. 

This is stated in a statement following the meeting with Turkish leader Tayyip Erdogan at G20 summit in Osaka, distributed on Saturday by White House.

He “encouraged Turkey to work with the United States on defense cooperation in a way that strengthens the NATO alliance.”

The two leaders also discussed the desire to improve bilateral trade and achieve common goals in Syria.

The US is actively trying to prevent Turkey from acquiring the S-400s. Earlier, Washington has already warned Ankara that it may refuse Turkey to supply F-35 fighter jets if the deal with Russia would come into force.

On Saturday, Erdogan, at a meeting with Russian President Vladimir Putin, said that there were no delays in the delivery of the S-400s to Ankara. According to him, an agreement on joint production of missiles and the transfer of technology is a priority for Turkey.