This is not an example of that. It is perfectly within US jurisdiction to prevent US companies from doing business with sanctioned countries. That is the point of a sanction, and US is in good company in choosing to use sanctions as a diplomatic tool.

It is more of an example of how the internet/software industry is too consolidated to the US, and thus other countries are too dependent on the US in those areas. If the internet infrastructure was well distributed, then people in sanction countries could simply get certificates issued by a different CA, and in some cases they can. However, this is complicated by the fact that the list of trusted CAs is dominated by US organizations (Google, Mozilla, Apple, Microsoft). If you want to reach western audience you must use certs from a CA approved by them.

Exactly. Ever since I was a kid I never understood how the US has jurisdiction way beyond their borders.

Then I graduated in International Relations and understood that the hole is much deeper than that.

Now it's pretty obvious with all the shit that trump has been doing, but back then me and much of the people I know were oblivious to what US power really means.

The only countries that do not have sanctions are the ones who lack the economic leverage to do so. All developed countries have them.

US law is something US citizens get to decide. If they think it's "batshit", they should vote accordingly. In this case sanctions seem a pretty good alternative to going to war.

This is not specific to US law ...