Do casualties affect troop deployment?

Economists assume that people always act rational in the sense that for every decision a person makes, this person compares all relevant costs and benefits and will only engage in the action if the latter exceed the former. Hence, a rational policy maker will only choose for a particular option if the benefits exceed the costs. Economists also assume that people are selfish meaning that they only take into account their private benefits and costs. When benefits and/or costs are of a public nature, individuals are not always assumed to act in favour of this public welfare and decisions become more difficult. Since security and peace are standard examples of a public good, foreign policy decisions are largely influenced by public benefits. The costs of the instruments such as of a military deployment are however mostly of a private nature. Next to the direct monetary price of military interventions, the probability of loosing soldiers is also an important cost. When the number of casualties is high, the private cost of a military intervention rises, potentially forcing policy makers not to deploy or to withdraw troops.
The withdrawal of Western troops after the disasters in Ruanda and Somalia in the 90s provides anecdotal evidence. Former Secretary General of the UN, Kofi-Anan, referred to this effect as the ‘post-Somalia syndrome’ (Mays, 2003). While this ‘post-Somalia syndrome’ is often referred to as an important factor contributing to the decrease in personnel contributions to peacekeeping operations, this study is the first to our knowledge to actually test for its existence.