Foreign Policy magazine has an article by Daniel Kahneman and Jonathan Renshon on the role of cognitive biases in the decision to go to war.
Kahneman is a nobel prize winning psychologist known for his work on decision making and Renshon is a political scientist and author of the book Why Leaders Choose War: The Psychology of Prevention (ISBN 0275990850).
Social and cognitive psychologists have identified a number of predictable errors (psychologists call them biases) in the ways that humans judge situations and evaluate risks. Biases have been documented both in the laboratory and in the real world, mostly in situations that have no connection to international politics. For example, people are prone to exaggerating their strengths: About 80 percent of us believe that our driving skills are better than average. In situations of potential conflict, the same optimistic bias makes politicians and generals receptive to advisors who offer highly favorable estimates of the outcomes of war. Such a predisposition, often shared by leaders on both sides of a conflict, is likely to produce a disaster. And this is not an isolated example.
The article is an interesting attempt to apply knowledge of cognitive biases to understanding political decision making in high stress, high stakes situations.
This is an area which is becoming increasingly important in military psychology. Both to understand how individual soldiers might make battlefield decisions, and how leaders might make strategic choices during conflict.
Link to article ‘Why Hawks Win’ (via Frontal Cortex).
Mind Hacks 
Daniel Gilbert wrote an op-ed piece for the NY Times about biases that lead to war in the July 24, 2006 issue. He gives two moral rules – you can morally act against someone if they act against you first and a moral response must be commensurate with the offending action.
The problem is that we remember the causes of our own actions, while we remember the consequences of others’ actions. And our pain is much more real to us than others’ pain. These biases result in invasions and disproportionate military responses.
I also recommend watching Michael Shermer’s presentation on ted.com. He is the founder of Skeptic magazine. He demonstrates the power of priming and upping-the-ante to produce perceptual blindness. I think that the US media hype leading up to the US invasion of Iraq was an example of this.