I can't find the link but I read a good article recently about how the internet could go out. in summary if there was a convential war some country(ies) could bomb/blow up certain pipes underground and it would effectively cut the internet off.
to stop the internet now would involve the complete destruction of every electronic device. so back to the middle ages or 1)supervolcano (overdue) meteor or comet (50-250 yrs)E.L.E. not even all out nuclear war would destroy btc because of shelters. thats it I think. reg
If we consider the internet to be GLOBAL communication system, then yes it's possible to break it, at least where you no longer have a global communications system.
We rely on a small number of underground cables and a small number of central internet exchanges. It would in theory be possible to create widespread disruption without the need for a global catastrophe.