The Increasing Response Options and Deterrence of Missile Engagements Act of 2025, or the IRONDOME Act of 2025 , seeks to substantially improve the United States' missile defense capabilities in response to rapidly expanding and sophisticated missile threats from nations like China, Russia, and North Korea. Congress finds that these threats, including ballistic, cruise, and hypersonic weapons, necessitate a comprehensive, next-generation missile defense shield to protect the homeland and critical infrastructure. The bill emphasizes that missile defense is a core deterrence-by-denial component of an integrated deterrence strategy, adding resilience and undermining adversary confidence in missile use. Key provisions include accelerating the development and fielding of various advanced systems. The Secretary of Defense is directed to expand Next Generation Interceptor production and silo construction at Fort Greely, Alaska, aiming for a minimum of 80 interceptors by January 1, 2038. The bill also mandates accelerating the development of the Glide Phase Interceptor to defend against hypersonic threats, and the production and fielding of the Terminal High Altitude Area Defense (THAAD) system , including AN/TPY-2 radars. Furthermore, it calls for accelerating the development of autonomous agents for cruise missile and drone defense, and proliferated space-based interceptors capable of boost-phase intercept. The legislation also focuses on modernizing existing infrastructure and strategic planning. It requires the Secretary to accelerate the modernization of terrestrial-based radar capabilities, such as Cobra Dane and the Alaska Radar System, and the Perimeter Acquisition Radar Attack Characterization System (PARCS). Plans are mandated for a southern hemisphere-facing early warning radar system and the construction of East Coast and Alaska-based Aegis Ashore missile defense systems . Additionally, the bill requires a multi-year plan to transfer missile defense operations and sustainment responsibilities from the Missile Defense Agency to military departments, allowing MDA to focus on research and development. To support these efforts, the bill authorizes the procurement and fielding of dirigibles for homeland missile defense and accelerates the production of critical munitions like SM-3 Blocks IB and IIA, and PAC-2 and PAC-3. It grants expedited military construction authority, allowing the waiver of regulations for urgent operational needs. The Act also directs the acceleration of integrated air and missile defense technology exchanges with trusted allies and the development and securing of supply chains critical to missile defense component production. For fiscal year 2026, the bill authorizes an appropriation of $19,548,100,000, with specific allocations for various programs including interceptors, radars, and research and development.