Perhaps it is useful to observe the other way: the main reason why China has both huge surplus in trades, and largest STEM students is that China is an island of Producer, instead of Consumer as US is, quoting Warren Buffet's analogy. So naturally there is a need for large numbers of STEM graduates to fullfill needs of such Producer. It is not possible for US to produce such large number of STEM students because there is no market for it (except for some small niches, such as computer, and biotech where US has such needs). So as a policy, just promoting more US students to study STEM will not succeed unless there is a market need for hiring them first. It is kind of chicken and egg problem, but I think fundamental problem is US is no longer producing things.