Although research indicates that verification is critical for successful nuclear weapons agreements, some scholars and policymakers are skeptical that transparency can ever be achieved. This chapter asks whether states can reach credible agreements without verification. Beyond monitoring institutions, many pacts require destruction of program infrastructure, which adds to the cost of future violations. I show that such cost increases in the form of moderate nuclear reversals incentivize opponents to cut deals that ultimately leave all parties better off. Arms treaties therefore primarily benefit potential proliferators, not their opposition. I apply these findings to help explain features of the recent Joint Comprehensive Plan of Action (“Iran Deal”).