Current U.S. national security execution mechanisms, conceived and resourced for a Cold War security environment, now exhibit a systemic inability to achieve national strategic objectives in the dynamic post-Cold War era. This policy analysis proposes the statutory establishment of interagency deliberate planning as a necessary and practical first step to mature interagency execution. The primary purpose of this initial step is to evolve national-security-related operations from mere coordination of individual agency efforts to an objectives-oriented synchronization, integration, and interdependence of combined interagency operations. The secondary purpose of interagency deliberate planning is to identify specific capability gaps and overlaps that may then be resourced appropriately over time within an integrated and prioritized national security budget. The article presents this proposal by leveraging the extensive body of national security reform literature to characterize both the problem and the major categories of options already proposed. The article then draws a parallel between the unity of effort challenges now faced at the interagency level with those successfully addressed on a smaller scale among the military services through reforms in the Goldwater-Nichols Department of Defense Reorganization Act of 1986. Through this historical parallel, the authors highlight the portions of the Goldwater-Nichols Act reforms that established clear strategy-to-task links between ends, ways, and means as the most prescient missing ingredients now required to achieve interagency unity of effort. Finally, the article establishes a rationale and action plan for implementing interagency deliberate planning in a manner that is responsive to the systemic problems identified and overcomes the barriers that have frustrated significant national security reform in the recent past.