In two previous posts, I made estimated projections forward in time of the number of U.S. Navy ballistic missile defense (BMD) capable ships and the number of SM-3 BMD interceptors. These projections reached two main conclusions: (1) The number of BMD capable ships would reach the upper seventies (77) by 2040; and (2) The number of SM-3 Block IIA interceptors (including possible more advanced version of the missile) would be in the hundreds, possibly 500-600 or more, by the mid-to-late 2030s.
Several developments since those posts were written illustrate the uncertain nature of such projections. In February 2016, it was revealed that the Navy had decided to upgrade three additional Flight IIA Aegis destroyers to the full advanced BMD capability (under the previous plan these three ships would have had no SM-3 BMD capability). In addition, it is still unclear how long the five Aegis BMD cruisers will remain in service, although this makes no difference to the longer term projections..