Hi csl,
To the extent such a law is extra-territorial, it should not stand.
If he was a man of integrity, he would have made such an order through the normal law-making mechanisms.
Presumably, he is using it to scare folks who didn't support his Jerusalem initiative.
To this extent, it will generate more hatred for the US around the world, which means less influence.
Heck, even the UK couldn't stomach siding with Trump over Jerusalem.