War's bad, but some things are worse.
Genocide and other large-scale one-sided killing: in war, at least you have two sides shooting at each other, whereas in this scenario one side does all the killing and the other side does all the dying. (Usually preceded by or done in conjunction with war, but not necessarily.)
Terrorism: in war, militaries attempt to force policy goals by destroying their opponents' ability to resist. Terrorism by contrast tries to force a policy goal by targeting innocent bystanders. Whatever overlap exists is optional for war (a military doesn't have to target civilians) and accidental for terrorism (which primarily targets civilians).
Hell: real or not, as popularly described ("lake of fire; eternal torment") it's worse than war.
Borderline are small-scale but high-impact crimes against innocent people, like a serial killer who tortures 50 people. It's pretty bad for those people, and for all their friends and family, but probably not the entire country... unless it's a small country, which there are lots of.