There was a war over a piece of alien technology. Both sides wouldn't give up wanting it, and millions were dying. So, the Nadesico stole it and sent it to a place no one could find it, so there was nothing to war over anymore.

We weren't associated with either military at that point as we stole the Nadesico when the orders we got were exceptionally stupid, and after both sides calmed down things got a lot better.