Which document outlines the U.S. policy on foreign military sales (FMS)?

The Security Assistance Management Manual (SAMM) is the definitive document that outlines U.S. policy and procedures regarding Foreign Military Sales (FMS). This manual provides comprehensive guidance on the management of security assistance programs, including the legal framework, the roles involved, and the steps for implementing FMS transactions. It serves as the primary reference for foreign military sales operations, ensuring that all stakeholders understand the requirements and processes involved in such transactions.

While other documents like the National Security Strategy, the Defense Authorization Act, and the Department of Defense Directive provide important context and overarching policies related to U.S. defense and foreign relations, they do not specifically focus on the FMS process. The NSS addresses broader strategic interests, the DAA deals with budgetary and funding issues for defense, and DoDDs provide guidance on specific departmental policies but are not dedicated to the details of FMS. The SAMM is essential for anyone involved in foreign military sales, making it the correct answer in this context.