What does Kurt Vonnegut say about war in his novel Slaughterhouse-Five?

Vonnegut doesn't actually make any direct statements about
the war in the book, though of course he is obliquely trying to bring out the absurdity
and some of the moral rot that surrounds war and the decisions people make and then
justify during wartime.  The centerpiece of the book is the fire-bombing of Dresden,
something he witnessed first hand and something that had a profound effect on
him.

There are many things he does that comment on the war,
the willingness of the Tralfamadorians to not worry about people dying and the way that
they can simply ignore the bad things and focus on the good in their ever-present
world.  But mainly I think he points to the absurdity of it through the way he tells the
story.