"... when they do not serve American interests"
Now there's a phrase coined by a lying weasel.
Newsflash, the visas wouldn't exist in the first place if they didn't "serve American interests". The question is, which American interests? Because the management and shareholders and customers of the companies who benefit from these lower prices - they're Americans too.
So, which specific group of Americans will Trump tell the gov't to bestow its patronage upon?
Trump understands all about patronage. Just look at his TV show.