How to evaluate compliance is among the most difficult questions that arise during treaty negotiations and ratification debates. Arguments over verification principles and procedures are increasingly common for accords about the environment, human rights, and economics, but they have been especially important in the arena of national security. Nancy Gallagher explains, -In a world in which states face conflicting pressures to maximize military capabilities and negotiate mutual restraints, the prospects for arms control often hinge on verification... In the standard American formulation,...