This struck me as like an angry eighth-grader’s tweet.

I don’t really know how to make sense of it because I don’t think he can do this even if he wanted to.

It probably violates NAFTA [the US trade deal with Mexico]. I don’t think he’ll have much if any support in Congress. Nor do I think logistically he’d be able to implement it.

And when you start throwing out vacuous threats like this, people stop taking you seriously in terms of how you go about negotiating.