(at one point Trump requested that only a "friendly" reporter from Turkey ask questions of Erdogan), that the touchy subject of Turkey's acquirement of Russia's S-400 anti-air system was front and center in closed door conversations. 

But Erdogan appeared unmoved by whatever pressure he may have faced in the Oval, given he later told reporters while standing next to the US president that Turkey cannot possibly discard the S-400 due to its strategic ties wit Russia, but he also added, "I've told Mr. Trump that we're ready to buy Patriots."

And according to Bloomberg, his only hint at "compromise" came in the form of offering to participate in a NATO-coordinated working group where defense officials from both sides would resolve issues of top concern for the alliance related to NATO's second largest military deploying a Russian advanced system on its soil.