The United States needs a new strategy for missile defenses, one that reflects the changing international environment and military requirements. Our original construct for the development and deployment of missile defenses was based on the strategic relationship that developed between the United States and the Soviet Union during the Cold War. In that period the threats were well-known, the major avenues of attack clearly defined and the technologies of interest constrained by arms control agreements. Strategic defenses played a poor second to strategic offensive forces in the maintenance of U.S. and allied security.
The Bush Administration shattered the old consensus on missile defenses. Withdrawal from the Anti-Ballistic Missile (ABM) Treaty opened the way to the development of unconstrained systems and architectures. The decision to remove Russia from the top of the list of potential threats allowed missile defense strategists to focus on more immediate and, fortunately, limited threats. Years of intensive research and development have resulted in the deployment of several effective systems and the promise of still better capabilities in the near future.
The Obama Administration has the opportunity to develop a new strategy for missile defenses, one consonant with current strategic realities and their own inclinations with respect to foreign and security policies. It needs to think creatively about the role of missile defenses in support of plans for global denuclearization.
This new U.S. strategy for missile defenses must reflect a number of factors:
• A less predictable threat;
• An increasingly flexible – perhaps even fragile – set of international relationships;
• Growing reluctance on the part of allies and friends to accept significant and long-term U.S. military deployments on their territory;
• The growth in so-called anti-access threats; and
• The new opportunities to develop unconstrained missile defenses.
Such a new strategy must emphasize flexibility, the ability to apply graduated pressure on potential attackers and low visibility so as to not cause problems for friends, allies and negotiating partners. Defensive deployments can provide additional political as well as military options as a crisis with a missile armed adversary unfolds.
Any U.S. missile defense system needs to be multi-layered. Terminal defenses alone are insufficient operationally and leave the initiative in the hands of the attacker. An attacker can hope to overwhelm a terminal system or simply force the defender to play a guessing game with respect to what targets to defend. Even if an intercept is successful, a terminal-only defense still permits debris to rain down on an area around the target.
Layered defenses offer a number of advantages including more engagement opportunities, the ability to use different phenomenology and attack mechanisms against the missile or its payload, the ability to undermine countermeasure strategies, and the ability by the defense to apply preferential engagement strategies. A layered system takes the initiative away from the attacker. The more layers there are, the more effective the defense and the greater the ability to both defeat an attack and defend targets.
Mobility is another characteristic that should be part of any missile defense architecture. Mobile defenses can respond to changes in the threat, reinforce fixed defenses or address the emergence of new threats. Mobile defenses can be less politically difficult for friends and allies to accept than fixed deployments.
With the addition of boost phase systems, the United States will be able to provide a layered defense and seize the initiative from the attacker. A boost phase system operates in that portion of the flight trajectory when a ballistic missile is most vulnerable and countermeasures the most difficult to employ. Boost phase defenses are particularly useful against long-burning missiles such as those being developed by North Korea and Iran. At the same time, a boost phase system is relatively less effective against shorter-burning missiles such as those deployed by Russia.
A boost phase capability is particularly valuable in the absence of adequate midcourse discrimination or in the presence of complex threats employing countermeasures. A boost system will still need capable sensors to provide rapid and accurate target tracking.
Mobile boost phase defenses are important because they provide strategic agility, operational flexibility, low visibility (until needed), and reassurance to allies while imposing uncertainty on the attacker. Depending on the type of boost phase weapon system that is available, potential deployment locations can be predetermined and supporting capabilities deployed without raising the overall visibility of the commitment to defend forward. One can even imagine potential control regimes that would define the conditions under which certain boost phase systems could be deployed.
A mobile boost phase missile defense capability would provide the White House with additional options in dealing with ballistic missile proliferation. The U.S. Navy already can provide the Administration with the option of deploying sea-based terminal defenses in the Persian Gulf to counter an Iranian ballistic missile threat to allies such as Kuwait and Saudi Arabia. The addition of a mobile boost phase capability would provide an option for the protection of more distant friends and allies and thereby, perhaps, obviate the need for the United States or others to take more extreme measures.
Looking at the kinds of threats a layered defense can be expected to face over the next decade, boost phase systems should have certain characteristics:
• Flexibility in deployment;
• Large area coverage; and
• Speed of engagement.
Today, the only system with any boost phase capability is the Aegis Ballistic Missile Defense System (BMDS). A sea-based boost phase system is certainly desirable. Sea-based systems are inherently mobile and have the security associated with operations in international waters.
There is only so much that can be done with the Aegis BMDS. Given the speed of the current Standard Missile (SM-3) variant, the ship must be precisely positioned in order to have any realistic chance of engagement in the boost or ascent phase. Moreover, there are a number of potential threat trajectories that are inaccessible from a location at sea.
To pursue a boost phase strategy, the Obama Administration will have to invest in other systems. One potential candidate is the Airborne Laser (ABL). Not only could the ABL engage ballistic missiles in boost, it could also address other types of targets. Clearly, the ABL has the advantage of strategic mobility and tactical flexibility. Any major airfield can serve as a forward deployment base for the ABL.
Another candidate with a great deal of promise is the Kinetic Energy Interceptor (KEI). KEI has the advantage of being the first missile defense system to have been designed from the start free of the constraints imposed by the ABM Treaty. Unlike the ground based midcourse interceptor, the KEI can be deployed in a mobile configuration. Like the ABL, KEI does not require an external sensor to perform an engagement. Potential deployment sites can be pre-surveyed. Reassurance could be provided by periodic deployment exercises. A sea-based variant is also an option. KEI has both the range and speed to be a highly effective interceptor in the boost/ascent phase. It could supplement a European Third Site or the Aegis BMDS or provide a stand alone capability.
Deployment of a serious boost phase system could pose a significant deterrent to the plans by countries such as North Korea and Iran to develop long-range ballistic missiles. A boost phase system presents would-be proliferators with the reality that the defense will be able to take multiple shots at any attacker, significantly increasing the chances of interception. With a boost phase defense in place, midcourse and terminal countermeasures become largely irrelevant. Also, the attacker must consider the possibility that debris from a successful “hit” by the defense will land in his lap.
Credible options exist to build a layered missile defense system around highly effective terminal systems and one or more boost/ascent phase systems. The mobility inherent in the Aegis BMDS, ABL and KEI would support the development of operational concepts and support security policies that fit the demands and constraints of the 21st Century. In addition, it is possible to conceive of arms control regimes for mobile defenses that ensure stability and predictability while also providing reassurance to friends and allies.
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