He blustered, threatened, provoked before sitting down with Xi. The world and the Chinese were scared/gravely concerned he would start a trade war. Scared/concerned he would crash the stock market and start a world-wide recession. Terrified. We don't know the details yet, but my guess is that Trump used this rhetoric to get what he wanted out of the Chinese and the Chinese felt good about it because they feared much, much worse. Trump's strategy in negotiations is to always start with outrageous positions and negotiate backward. His theory is that you end up getting much more than you ever imagined.
https://www.yahoo.com/news/chinese-state-media-cheer-xi-trump-meeting-confrontation-082322893.html
https://www.yahoo.com/news/chinese-state-media-cheer-xi-trump-meeting-confrontation-082322893.html