I'm reading Out of Control: The New Biology of Machines, Social Systems, & the Economic World, a most excellent book about complexity. This quote caught my eye:
In defending itself so thoroughly against the monarch, the milkweed became inseparable from the butterfly. And vice versa. Any long-term antagonistic relationship seemed to harbor this kind of codependency. (p 74)
This made me realize something about the nature of governments and war: Governments evolved to protect resources and people from the threat of outside invasion. An organizing structure was required to create and maintain a fighting force capable of resisting invasion from neighbors. However, it's now obvious that governments are in a codependent relationship with war: If there were no more war, then there would be no need for a government's ability to organize a fighting force. Therefore it's in a government's best interest to ensure that war never ceases.
However, just like any other codependent relationship, a lot of denial takes place. I doubt most politicians would come out and say that a prime function of government is to create war. Actions speak louder than words, though, and it's clear that in the thousands of years of human civilization there have been plenty of wars.