Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress [June 5, 2017] [open pdf - 1MB]
"The Aegis ballistic missile defense (BMD) program, which is carried out by the Missile Defense Agency (MDA) and the Navy, gives Navy Aegis cruisers and destroyers a capability for conducting BMD operations. Under the FY2017 budget submission, the number of BMD-capable Navy Aegis ships was scheduled to grow from 33 at the end of FY2016 to 49 at the end of FY2021. The figure for FY2020 may have included up to four BMD-capable Aegis cruisers in reduced operating status as part of a program to modernize 11 existing Aegis cruisers [...] Issues for Congress regarding the Aegis BMD program include the following:  required numbers of BMD-capable Aegis ships vs. available numbers of BMD-capable Aegis ships;  whether the Aegis test facility in Hawaii should be converted into an operational Aegis Ashore site to provide additional BMD capability for defending Hawaii and the U.S. West Coast;  burden sharing--how European naval contributions to European BMD capabilities and operations compare to U.S. naval contributions to European BMD capabilities and operations;  the lack of a target for simulating the endo-atmospheric (i.e., final) phase of flight of China's DF-21 anti-ship ballistic missile; and  technical risk and test and evaluation issues in the Aegis BMD program."
CRS Report for Congress, RL33745
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html