Defence Expenditures by Countries in Allied and Adversarial Relationships

This paper models the linkage between a country's national security and the defense spending of its allies and adversaries. The cost of an arms race is introduced into the alliance public good framework of Olson and Zeckhauser. Contrary to their presumption, for a cooperative treaty to increase defense spending in an alliance may make it worse off. Further, even where the treaty makes an alliance better off, such treaty making may constitute a form of prisoner's dilemma for the world as a whole.