Yes, the monitoring can be done remotely but resolving injected problems requires hands and feet on the spot. If an adversary took a 'distributed stuxnet' approach to infrastructure dislocation, each implemented attack vector would need to be diagnosed and resolved on a case by case basis. The complexity scale is only limited by their imagination and ability to populate terror cells. One line may have derailment wedges attached. Another electrical error devices. A third pennies in sensors. A fourth some pipes they took from a dumpster. As the campaign escalates its reasonable to expect explosive ordinance to be associated with each attack. A smuggled grenade or homemade pipe bomb to injure repair crews. An acid spray to blind electricians. And the list goes on. The only genuine solution is to treat national security as a whole of society effort and have genuine popular support for the defence of the realm. Anything else is accepting defeat before a shot is fired.