I was talking with some buddies on another site, one of them actually brought that up. When the machines wipe us out, it will be because we're too annoying, like mosquitoes, not because we are dangerous.
Is this your homework?
Actually, that is a perfect example of what I meant with #2. Two cities were destroyed, and it effectively ended WW2. Humans are now so terrified of nukes that the idea of nuclear war is so horrible we can't even imagine it happening (at least, not on a large scale. How many people worry about a nuclear terrorist attack?)
UEF-United Earth Federation
Well there wasn't much left of WW2 to fight. Italy was defeated. Germany was defeated. And Japan was defeated, they just weren't willing to admit it yet. They didn't really end the war, they simply shaped how the war ended (surrender as opposed to invasion).
Humans aren't really terrified of nuclear weapons. We are terrified of anything with the words "nuclear" in it.
Plus there is no reason to be terrified of nuclear weapons. As anyone over a certain age will be able to tell you, all you need to do to survive one is duck under a school desk. Rather over-hyped weapon when you think about it.
I'm more of a fan of the Terran Federation.