There are plenty of examples in recent history of underground resistance being incredibly tough to crack. It may seem nonsensical, but people to this day are doing it very well against tanks and drones and bombs. The US has more firearms than people. People are not subdued by tanks and drones. It takes other people to actually take a foothold in some territory. I bet you can imagine how much tougher that would become against a group that was well armed and supplied, dug in, and fortified (their own backyards). I don't think it is nonsensical at all.