The militia is a form of Vyseni rebels who live in the "Shelled School" during the rebels scenario. There is an event a few days after agreeing to help your neighbour Valter loot a humanitarian aid box, where the rebels would go to your shelter to confirm their suspicions of Valter looting the aid box. If you say no, some of your characters morale would increase. If you say yes, then your characters may also become sad but there is a reward containing cigarettes, food and supplies if you snitch on Valter. After the event, it is possible that Valter would get killed by them.