2013-03-26 by Richard Weitz
For decades, U.S. strategy has been to defend the territory of the United States, its people, U.S. allies, and U.S. military forces deployed overseas against a deliberate, accidental or unauthorized ballistic missile attack.
The United States has been developing and deploying a range of BMD systems over the years.
After decades of research and development, some early technologies have reached maturity while others are already contributing to achieving these goals. The hit-to-kill concept has proven reliable in many tests and in some limited operational engagements despite initial incredulity by some about being able to “hit and bullet with a bullet.” Other BMD capabilities are now in development that would bolster these existing BMD assets.
If developed and deployed in a timely manner, these new BMD capabilities should prove able to match expected improvements in adversaries’ missile capabilities.
But for the next few years, the best option would be for the United States to continue to construct the ground-based mid-course defense system (GDM) while developing improved versions of the land-based and sea-based Standard Missile (SM-3) as a complementary second layer of the system.
U.S. BMD systems make several critical contributions to U.S. security.
- defend the American homeland, U.S. forces and citizens located overseas, and U.S. friends and allies
- deter such attacks by enhancing both the capacity and the perceived will of the defender to thwart any aggression
- dissuade potential aggressors from seeking to acquire and deploy ballistic missiles or nuclear warheads by reducing their relative perceived value
- reassure U.S. friends and allies, which contributes to other perceived goals such as strengthening these ties and dissuading them from obtaining nuclear or other retaliatory weapons
- counter anti-access/area-denial (A2AD) and other asymmetric strategies and tactics designed to employ ballistic missile capabilities to negate U.S. conventional superiority, thereby ensuring U.S. access to the global commons.
Ballistic missiles can be placed into four categories based on their range:
- intercontinental ballistic missiles (ICBMs) that can reach the continental United States (ranges exceeding 5500 km)
- intermediate-range systems (3000-5000 km) that can threaten many regional allies and forward-based U.S. forces
- medium-range missiles (1000-3000 km) under the possession of a growing number of countries
- short –range missiles (less than 1000 km) designed primarily for battlefield use.
The Ballistic Missile Defense Review (BMDR) predicts that the missile threats to the United States and its friends and allies will grow in quality and quantity as antagonistic states increase the size and capabilities of their ballistic missiles.
More than 30 countries already have, or are acquiring, ballistic missiles that can carry not only conventional warheads but also unconventional payloads with nuclear and other weapons of mass destruction. Most of these programs are developing short- and medium-range missiles with conventional payloads, but longer-range missile capabilities will also become more widely available in coming years.
Missile intercepts can generally involve one of three phases of the missile’s flight. A boost phase intercept hits a missile immediately after launch, before it has had time to enter space and deploy its warheads and decoys. Although the target is very hot and visible, a boost intercept requires that the interceptor launcher is located very close to the launch place and that the interceptor can launch very quickly and rapidly accelerate to catch the newly launched missile before it too accelerates beyond reach.
A mid-course interception hits a missile in outer space. There is no need to be close to the missile launch site and the defender has time to target and hit the delivery vehicle in flight, which often is in an easier calculable ballistic flight. But the problem of discriminating the warhead from decoys and pieces of the rocket and other debris is severe.
A terminal intercept aims to hit the warhead as it approaches the target, when its trajectory is better known and the warhead is more easily distinguishable from any decoys and debris. If the interceptor is at the location the warhead is descending upon, then the interception is more likely. But if the warhead comes down in an unexpected location, is able to maneuver in flight or take other countermeasures, or if it detonates above its target, the defender will experience more difficulties.
The United States has been developing a multi-layer defense system designed to attempt all three types of intercepts to maximize the possibilities of destroying incoming missiles. The U.S. Ballistic Missile Defense System (BMDS) architecture includes networked sensors, especially ground and sea-based radars for target detection and missile tracking. It also has ground and sea-based interceptor missiles for destroying a ballistic missile using either “hit-to-kill” technology, or an explosive blast fragmentation warhead.
The current BMDS interceptors for the various missile flight phases are the Ground-based Midcourse Defense (GMD), Terminal High Altitude Area Defense (THAAD), PATRIOT Advanced Capability-3 (PAC-3), and the Aegis BMDS. More advanced BMD systems using non-kinetic means are still under development.
Thus far, the demonstrated capabilities for the mid-course interception have proved superior.
Efforts to develop advanced boost-phase systems (such as an airborne laser) have made only limited progress. Battlefield terminal defenses have a better record, both in tests and actual operations, but their area of protection is limited. In contrast, the Aegis radar combined with the SM-3 interceptor has managed to hit a variety of targets under various testing conditions, as well as successfully shoot down a wayward satellite. The Aegis/SM-3 combination has been deployed on many naval platforms, and is being developed and deployed as a land-based system as well.
Ironically, due to the success and value of existing BMD technologies, the United States faces the challenge of balancing the need to continue developing and testing more advanced BMD technologies against the demand to field already proven current-generation systems.
Budget stringencies also magnify the challenge of juggling investments in augmenting BMD capabilities with pressure to field and operate existing systems.
Potential adversaries are deploying current-generation missiles that can be addressed by present-day U.S. BMD systems.
But they are also developing more advanced missile capabilities that require more advanced defenses to counter.
But the U.S. Department of Defense (DOD) wants to do more.
Even before the current sequester went into effect, the Pentagon’s January 2012 Strategic Guidance warned that, “Despite its importance, we were not able to protect all of the funding in this area. We protected investments in homeland defense and the Phased Adaptive Approach for missile defense in Europe aimed at protecting our allies.We reduced spending and accepted some risk in deployable regional missile defense and will increase reliance on allies and partners in the future.”
The United States has missile defense cooperation programs with the Japan, Israel, Australia, and many European countries. The traditional U.S. strategy is to develop military capabilities and conduct military operations in partnership with other countries, but to have the will and means to act unilaterally if necessary.
Also see the following: