The following is the Dec. 13, 2018 Congressional Research Service report, Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress.
From the report
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 FY2019 budget submission, the number of BMD-capable Aegis ships is scheduled to be 41 at the end of FY2019...