I doubt Trump cares. IMO, this is just another PR move. Trump's base will eat it up without the faintest notion of its actual impact.
Yeah...who the hell knows what/why Trump is doing and what he wants. After forcing a shutdown by shooting down bipartisan deals, while saying beforehand he would sign whatever congress could work out...He is all over the place.
Is he trying to distract from the Mueller investigation? Does he want a trade war? Is he trying to limit the reach of solar power vs his simple minded already chosen winner: coal and oil. Is he using it as a bargaining chip to try and force the Chinese into doing more about North Korea. Who the Fvck knows. He thrives in deception and chaos.
He's been holding various economic things over the Chinese head since before he was even elected, and since he was elected he trots them out only to put them away once the Chinese make a concession. He's doing basically the same sort of thing with Mexico and Canada and NAFTA. It's basically his method for doing business...he likes having leverage and showing he has a big stick to hit someone with and uses it to threaten in order to get his way. He thinks he can run the US just like he does one of his businesses or even his personal relationships. It may be that you don't need to look for a more deeper or more convoluted reasons than he's a dick, acts like a dick, and this is how he does things.