"Though we have acheived progress, our work is not over. That is why I support the mission of the Arms Control Association. It is, quite simply, the most effective and important organization working in the field today." 

– Larry Weiler
Former U.S.-Russian arms control negotiator
August 7, 2018
Shorter-Range Missile Defenses Show Progress

Wade Boese

Despite continuing concerns about the capability and testing of Pentagon efforts to develop and deploy anti-missile systems to protect against long-range ballistic missiles, less controversial programs to counter shorter-range missiles are enjoying some success.

The Pentagon’s Missile Defense Agency (MDA) announced June 5 that it had conducted the second successful intercept test of a Standard Missile-2 (SM-2) Block IV interceptor. Fired from the USS Lake Erie stationed off Hawaii, that missile destroyed a descending target approximately 19 kilometers above the Pacific Ocean.

The Aegis SM-2 Block IV interceptor program differs from the more established Aegis SM-3 project. Both can be fired by the same ships out of the same launching tubes at shorter-range ballistic missiles. But the SM-2 Block IV is designed to counter missiles inside the atmosphere in the final moments of their flight, while the SM-3 is focused on destroying missiles in the exoatmosphere. In addition, the SM-2 Block IV employs a blast-fragmentation warhead that explodes near its target as opposed to the SM-3 interceptor, which releases a kill vehicle that is supposed to seek out and smash its target through a direct collision.

Based on Navy demands for an interceptor that could deal with ballistic missiles in their so-called terminal stage, the MDA and Navy agreed in 2006 to cooperate on the SM-2 Block IV project. A similar program, the Navy Area Theater Ballistic Missile Defense, had been cancelled in December 2001. The MDA is paying for modifications of the Aegis system to enable the firing of the new interceptor, and the Navy is supporting the necessary technical changes to an inventory of approximately 100 SM-2 Block IV missiles so they can perform the required mission.

Meanwhile, the older SM-3 interceptor program has scored 12 hits in 14 intercept tests, including the first-ever experiment last December by a Japanese ship. (See ACT, January/February 2008 .) A second Japanese vessel is expected to conduct another SM-3 intercept test later this year.

Japan is working with the United States to develop a longer-range version of the SM-3 intended to be more capable against long-range ballistic missiles that can travel further than 5,500 kilometers. That system is expected to be available for potential testing in 2014.

By that time, the MDA is hoping to have a fleet of 18 ships capable of launching the SM-3 as well as the SM-2 Block IV. Roughly a dozen ships can currently launch the SM-3, and the MDA is planning to have 38 of those interceptors available for potential use by the end of this year.

The MDA also is pushing ahead with development of the Terminal High Altitude Area Defense (THAAD), which is intended to counter missiles with ranges of less than 5,500 kilometers both inside and outside the atmosphere as they descend. On May 28, the MDA announced that the Army had activated the first unit that will operate the land-mobile THAAD system once it is ready for deployment in 2009 or 2010. Currently undergoing training through 2009, the unit will be responsible for three THAAD launchers and 24 interceptors. Current MDA procurement plans call for 96 total interceptors, but the agency has been pushed by lawmakers and the services to buy more of the interceptors, as well as Aegis SM-3 missiles. (See ACT, June 2008 .)

After failing in six of eight intercept tests between 1995 and 1999, the THAAD system went through an extensive program redesign. Since a 2006 return to intercept testing, THAAD has destroyed five targets in five attempts, including a June 25 test. In that experiment, the THAAD system achieved its first intercept of a separating target; previous tests involved missiles that remained in one piece during their flights.