As for the tunnels...collapse them...seismic sensors for general location and GPR for pinpointing them for demolition ought to be the standing order.
As for secession, I hope they are successful, it could initiate the Nationwide divorce from all the damned crazies. I'd be 100% for that! But the non-crazies will have to be sure to protect themselves from the crazies, because once they start realizing Proglodyteville ain't the utopia they thought it was, they'll try to escape. Best keep 'em bottled up!