Sea-Based Ballistic Missile Defense—Background and Issues for Congress

Ronald O'Rourke
Specialist in Naval Affairs

As part of its effort to develop an integrated global ballistic missile defense (BMD) system, the Department of Defense (DOD) has modified or is modifying several Navy Aegis cruisers and many Navy Aegis destroyers for BMD operations. DOD has also deployed a large BMD radar— the Sea-Based X-Band Radar (SBX)—on a modified floating oil platform. 

The proposed FY2010 defense budget requests a total of $1,859.5 million for the Aegis BMD program, including $1,690.8 million in research and development funding for the program and $168.7 million in procurement funds for the SM-3 interceptor missile. The proposed FY2010 budget would fund, among other things, the installation of BMD capability on six Aegis ships, which would increase the total number of Aegis BMD ships to 27. The proposed FY2010 budget also requests $174.6 million for continued operations of the SBX. 

On September 17, 2009, the Obama Administration announced that it wants to set aside the Bush Administration's proposed European BMD architecture and instead pursue a different European BMD architecture that would involve, among other things, a significant use of land- and seabased SM-3 interceptors and the Aegis BMD system. 

The eventual role of sea-based systems in the worldwide U.S. BMD architecture has not been determined. The overall issue for Congress discussed in this report is: What should be the role of sea-based systems in U.S. ballistic missile defense, and are DOD's programs for sea-based BMD capabilities appropriately structured and funded? 

The Aegis BMD system in its current configuration is intended to track ballistic missiles of all ranges, including intercontinental ballistic missiles (ICBMs), and to intercept shorter-ranged ballistic missiles. The current configuration is not intended to intercept ICBMs. Future versions of the Aegis BMD system are to include a faster interceptor designed to intercept certain ICBMs. The Aegis BMD system has achieved 16 successful exo-atmospheric intercepts in 20 attempts. This total includes two successful intercepts and one unsuccessful intercept by Japanese Aegis ships in three Japanese test flights. The Aegis BMD system has also achieved 3 successful endoatmospheric intercepts in 3 attempts, for a combined total of 19 successful exo- and endoatmospheric intercepts in 23 attempts. The Aegis BMD system was also temporarily modified and used successfully on February 20, 2008, to shoot down an inoperative U.S. surveillance satellite. Japan has acquired the Aegis BMD system, and some other allied navies have expressed an interest in adding BMD capabilities to their ships. 

Potential issues for Congress regarding sea-based BMD systems include oversight questions raised by the Administration's proposed new architecture for BMD in Europe, the number of SM- 3 interceptors planned for procurement, the number of Aegis BMD ships, whether development of a far-term sea-based terminal-defense BMD capability should be accelerated, technical risk in the Aegis BMD program, potential allied sea-based BMD programs, and whether development and testing of the Aegis BMD system offers any lessons for development and testing of other BMD systems.

Date of Report: December 22, 2009
Number of Pages: 80
Order Number: RL33745
Price: $29.95

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