It's really the futility of all war.

If there's one thing humanity can show to any other existing species out there in the universe that can demonstrate we are worth engaging with, it's the basic skill to overcome the instinctive need for violence.

http://www.thenation.com/blog/166080/futility-afghan-war

From commenter 'JTMcPhee' -

"...  We kill some of them, so they kill some of us, so we kill some more of them, so they kill some of us, so we kill some other ones over there, so they kill some of us ..."

Somehow I don't think we're there, or will get there anytime soon.