You misunderstand the job of these troops. Forward deployment like this are not there to threaten China. They are there, to tie down USA politicians. Suppose

You misunderstand the job of these troops. Forward deployment like this are not there to threaten China. They are there, to tie down USA politicians. Suppose China makes a move on Taiwan, now they have to play around US troops or fear bringing USA into the war. US politicians now have troops stuck in a war zone, they can no longer just was their hands of the situation - that would be politically unacceptable. Imagine if Russia had even symbolical amount of troops stationed in Gaza, Israel would be in a difficult position, indiscriminate fire can kill them and start an incident