Missile Defense: Better Oversight and Coordination Needed for Counter-Hypersonic Development, Report to Congressional Committees [open pdf - 6MB]
From the Highlights: "Since MDA [Missile Defense Agency] was established in 2002, the Department of Defense has spent over $174 billion to equip operational commanders with a network of sensors, interceptors and command and control capabilities collectively called the Missile Defense System. Since 2017, MDA's mission has broadened to include hypersonic weapons, which are difficult to track and defeat because they are capable of maneuvering during flight. Congress included provisions in legislation for GAO [Government Accountability Office] to annually assess MDA's progress toward meeting its acquisition goals. This report--the 19th to date--assesses (1) MDA's progress achieving its delivery and testing goals for fiscal year 2021, and (2) MDA's efforts to defend against hypersonic weapons."
Government Accountability Office: https://www.gao.gov/