S03E12: If It's Doomsday, This Must Be Belfast

To prove to Duke Nukem that the human race will self-destruct; Verminous Skumm steals and plants nuclear devices in war-torn areas across the globe. He then plays a little war gaming and gives triggers to the warring factions in those areas. With a potential Armageddon on their hands the Planeteers race to make the opposing sides in each location see peace before they act on war.