In the end, as in the beginning...violence!

"So the whole war is because we can't talk to each other.”         

"If the other fellow can't tell you his story, you can never be sure he isn't trying to kill you.”         

"What if we just left them alone?”         

"Ender, we didn't go to them first, they came to us. If they were going to leave us alone, they could have done it a hundred years ago, before the First Invasion.”         

"Maybe they didn't know we were intelligent life. Maybe--”         

"Ender, believe me, there's a century of discussion on this very subject. Nobody knows the answer. When it comes down to it, though, the real decision is inevitable: if one of us has to be destroyed, let's make damn sure we're the ones alive at the end. Our genes won't let us decide any other way. Nature can't evolve a species that hasn't a will to survive. Individuals might be bred to sacrifice themselves, but the race as a whole can never decide to cease to exist. So if we can, we'll kill every last one of the buggers, and if they can they'll kill every last one of us.”         

“As for me,” said Ender, "I'm in favor of surviving.”         

“I know,” said Graff. "That's why you're here.

The Ender's Game, chapter 13 - Orson Scott Card