>>64430095
That would nuke what little confidence the rest of the world still has left in the US administration, meaning a lot more domestic production and no more orders of F-35s or other military gear from the US. Which would in effect kill off a lot of american jobs as arms exports plummet and the US MIC having to downsize
TL;DR: Yes he could stop the engines, but it would be geopolitical suicide for the US.