With the right access it wouldn't be hard for someone to configure some key routers in such a way that all traffic is blocked and no one can get into them over

With the right access it wouldn't be hard for someone to configure some key routers in such a way that all traffic is blocked and no one can get into them over the network. They'd need to send someone physically to the sites to reset or replace them. I'm still leaning heavily towards an "oopsie" with routing that accomplished the same thing, however.