The US just gave a signal to China. No more quiet expansion.No Crimea 2.0. Taiwan will be protected. The US act early, they let things escalate early, they force China to state the true intentions. All this at a well picked moment while China is practically paralyzed because of the upcoming party congress preparing the next Xi term. They even managed to squeeze in a message to Kim with the Korea maneuvers.
This visit is obviously very well coordinated with the White House and well prepared. It is just diplomatically labeled to look a little less offensive in public. I call this a strategic message to China after the Ukraine and Hongkong experiences.