Foreign Military Sales The United States has sold to allies several types of BMD capabilities: Aegis tracking software, PAC-2 and PAC-3 batteries, and SM-3 Block IA interceptors (the last to Japan only). There is a potential for significant further sales if South Korea and Australia decide to emphasize BMD in future budgets, or if Southeast Asian countries such as Vietnam, the Philippines or Singapore begin to view ballistic missiles as a threat to their security. Even if these countries do not participate in a regional BMD system, some analysts have suggested that “reliance of non-U.S. assets on American hardware and software in systems like Aegis goes a long way toward syncing allied capabilities and interoperability [at the technical level].”82 A potential issue for Congress is what role, other than those already defined in statute; Congress would play a key role in overseeing Foreign Military Sales (FMS) of these BMD systems. Outlook for Near Term As the executive branch further develops U.S. BMD policy in the Asia-Pacific region, Congress has the opportunity to shape this development. The budget allocated to these BMD efforts will affect U.S. defense posture and capabilities in the region, and potential FMS financing of U.S. arms exports could help determine allied approaches to BMD. Through the power of the purse, oversight, legislation, or other tools, Congress may choose to encourage the evolution of an Executive Branch-led APPAA or other formal, collective BMD architectures, or it may choose to slow or thwart this current development. The degree of multilateral integration of BMD assets, accommodation of Russian and Chinese concerns, strategic focus, and technical foundation of BMD capabilities are just several of the critical issues that may merit congressional attention going forward.