If you think people volunteered to go off and get involved with war then you are possibly delusional. Most of my friends that joined the reserves (the ones that were supposed to be helping natural disasters really) volunteered to defend their country. Starting a war in Iraq was something they didn't volunteer for. And millions of killed civlians is something else they didn't volunteer for either.
I agree entirely, which is why I said that it wasn't a crime "against their own countrymen, at least." Everything else is distinctly less ambiguous, as you point out.