Also, if a zombie spawns in a neutral territory, each time a country’s combat phase begins, the zombies and the neutral territory’s standing army (if any) does 1 round of combat, zombies as the attacker. If used-to-be-neutral zombie territories are liberated by a player, that does not count as an attack towards a Neutral territory, so other neutral territories do not change their alignment to pro-axis/allies.
Do not forget to do the zombies attack (phase 2) for neutral territories as well.