Isn't that already the case? Or are you talking in terms of the government access to the worldwide internet?

The internet is not some single entity. It's a collaboration of all countries all over the world sharing their IP addresses with each other using open standard protocols so that everyone can talk to everyone. To get a single country cut off from the rest of the world would require active participation from every country around the world which is highly unlikely. At most you'd just have some or most countries participating in the ban.

What would happen to North Korea in that case? For the common people, nothing. They are already living with very limited and filtered access. For the government agencies that have full access, they would likely work a deal with a country to get the rest of the internet routed through them.

If you oppose the Kim regime, expanded internet access in NKorea would be a wise goal.

I suspect China would allow them access somehow.

So ignoring the technical problem of how it could actually be done, let's assume we somehow did it, cut every cable, and somehow blocked every cell tower and satellite from somehow connecting to North Korea to the rest of the world.

For the average north korean citizen, probably nothing much changes, most of them don't have much access to the internet to begin with.

For those who do, the elites, people in university, those government, military, etc. it will probably worry a bit.

For the elites who get to enjoy the internet as a luxury, probably not too much changes. I doubt that except for maybe the very top echelons of DPRK society, the Kim family for example (and maybe not even some of them,) anyone is getting totally unrestricted access to the global Internet. They're probably limited to mostly a bunch of north korean-hosted websites, and unless they're relying on data centers and such abroad (and they very well might be,) there's not really much we can do to take them down unless we really want to go in and attack all of the internal Internet infrastructure.

It's going to hamper their universities and such, sucks for them, probably no great loss for the world, the next big scientific break through probably wasn't coming from the hermit kingdom anyway.

It will definitely hurt their ability to conduct espionage, cyber attacks and such, that goes both ways though and it also makes it harder for other countries to spy on them.

They will do their usual sabre-rattling in response, maybe even going a bit above and beyond their usual mostly empty gestures, but probably nothing that's going to lead to any actual escalation p