NATO endured the end of the Cold War in 1991, its members deepened their commitment to the alliance, and it expanded considerably. Its survival fundamentally challenges the logic of realism, prompting two essential questions. First, is it possible to salvage realist alliance theory in the face of its apparent failure to explain NATO's continuing operation? This article contends that realism is repairable and salvageable in this context. Second, if realism is still a viable argument about NATO's endurance, how can it explain it? This article adds a complementary and still-missing explanation to realism based on economic incentives and gains. It argues that economic considerations such as the high cost and complexity to research, design, develop, and produce cost-efficiently modern, sophisticated, and technically complex weapon systems represented a substantial financial undertaking for NATO's great power members. The unparalleled economic burden prompted allies to pull resources together instead of seeking security unilaterally or through other alignment alternatives. The economic imperative of the modern defense industry is an essential and overlooked variable among realist and non-realist perspectives. Economic incentives affected in unprecedented ways the strategic calculus of NATO's great powers and, thus, causes their increased commitment to the alliance, its endurance, and expansion.