The United States has begun deployment of the its new SM-3 IB ballistic missile interceptor on U.S. Navy ships, according to an April 23 press release by Raytheon, the missile’s manufacturer.
The SM-3 Block IB interceptor uses the same propulsion system and missile airframe as the currently deployed Block IA version, but has a new kill vehicle with an enhanced infrared seeker, a faster processor and an improved divert and attitude control system. It has a two-color infrared sensor in its seeker (the sensor in the Block IA version uses only a single color) intended to provide increased discrimination capabilities. The new seeker also has improved sensitivity, giving it a greater detection range, and thus allowing engagement of longer-range targets. In addition, the Block IB kill vehicle also has a new, faster Advanced Signal Processor that “increases data processing capability to sort-out and analyze the information gathered by the upgraded seeker.”
The Block IB kill vehicle also has a new, “more flexible” throttleable divert and attitude control system (TDACS), which improves its divert capabilities. According to reports, the TDACS is able “to dynamically vary its thrust and operating time” and provides higher thrust levels using continuous thrust management to give a greater divert capability than does Block IA kill vehicle.
Although the Raytheon press release did not state which ship(s) the new interceptors were being deployed on, it did describe the deployment as “initiating the second phase of the Phased Adaptive Approach,” suggesting that at least some of them were on forward-deployed Aegis BMD ships in the Mediterranean or even on European-based ships. At present, the U.S Navy only has one Aegis BMD ship based in Europe, the destroyer Donald Cook, which is homeported at Rota, Spain. The number of U.S. Aegis BMD ships based at Rota is planned to increase to four by the end of 2015. (For comparison, there are already five U.S. Aegis BMD ships homeported at Yokusuka in Japan and U.S. Defense Secretary Chuck Hagel announced earlier this month that this number would be increased to seven by the end of 2017.)
 MDA, “FTM-18 Fact Sheet” June 22, 2012. Available at: http://www.mda.mil/global/documents/pdf/Aegis_FTM-18_FactSheet.pdf
 MDA, “Second-Generation Aegis Ballistic Missile Defense System Completes Successful Intercept Flight Test,” News Release, May 9, 2012.
 Zachary M. Peterson, “Raytheon, ATK Hope To Start Advanced SDACS Flight Tests This Year,” Inside Missile Defense, August 30, 2006; “Raytheon and Aerojet demonstrate SM-3 Throttling Divert and Attitude Control System,” PR Newswire US, August 15, 2006.