Who knows what Trump believes--John Bolton is likely the one pulling the levers here and he believes China poses a serious geopolitical threat to the long-term interests of the US and its allies. In between segments of Fox and Freinds--during various commercials peddling catheters--I'm sure he shouted some very meaningful words into Trump's ear and got his approval on pursuing this anti-China scheme. Some (like Gordon Chang and Peter Zeihan) have argued China is much weaker than it appears, especially given its opaque internal finances and goal of maintaining rapid economic growth via credit expansion in spite of the questionable returns on those underlying investments. Of course, bold projections of impending Chinese collapse could be easily overstated in an effort to sell books--however, there may some financial strain already forming. Speaking of Bolton, he seems to be trying to leverage the UK's awkward position with respect to Brexit with the enticement of a trade deal to enhance the US's hard-line on China & Iran.
You seem to be picking up many of the same frequencies as I do, but we have differing views on this.
I think Trump has demonstrated he doesn't really care what his advisers have to say if he has a gut feeling on something.
Early on in campaigning China was one of the key reasons he identified that America was losing. America was losing because China was winning, and cheating to win. He also mentioned that the US has long been contributing too much to NATO and our allies need to pick up some slack.
There's a decent amount of truth there. His tough talk on China while campaigning was no surprise; tons of candidates do that. And then they back down when they get elected. They know the havoc it could wreak on markets. Trump has a pretty big tolerance for haters and low polling numbers (even if he disputes them) and so he is in some ways one of the only presidents that has the stomach to stand up to China and risk tanking the market.
Why would it be worth the risk? The simple answer is that the world (and of course the US) is far better off with the US being the dominant economic superpower instead of China. China has manipulated its currency and executed a very focused effort on economic strength. Many suspect their goal was to de-industrialize other nations and that's probably not wrong. China's been averaging YOY double digit GDP growth since 1979, and they have leveraged their economic strength to expand their military footprint in disputed areas of the South China Sea. It would be foolish to think China is not interested in dominance.
The question then becomes when do we take action to prevent China from overtaking us? When each president has to factor in their own popularity and re-electability (during the first term) there are perverse incentives to kick the can down the road and focus on a more easily winnable legacy achievement.
It's kind of strange to assume that Trump is some type of obscure wonky paleo-conservative interested in supplanting the income tax. No, he just understands at a gut level that he cannot let China overtake the US as the economically dominant nation and so he's putting the screws to them as their growth story is slowing.
Obviously, Trump is otherwise a distractable and fear-mongering demagogue, so there's a temptation to write off all of his domestic and foreign policy gut feelings as hateful idiocy - but I think the blind squirrel has found the right nut on this one. If China wasn't so authoritarian and bent on gaining strength, I wouldn't feel this way. But I don't want dictator for life Xi Jinping calling the shots. I'd rather have the US with its constitution, checks and balances, and relatively superior human rights record calling the shots. And yeah, I'm a US citizen so I admit I'm a little biased.