Alien Stars

The Scapegoat – C.J. Cherryh
How can humans and aliens end a war which neither wants, when their ideas about war and peace seem to have no point of contact?

Seasons – Joe Haldeman
It was supposed to be a peaceful anthropological study of an alien race, but it went hideously wrong.

Cordon Sanitaire – Timothy Zahn
The aliens were beyond primitive: they were animals never seen to use tools in the wild – so why were they using weapons far beyond any invented by men?