Ballistic Missile Defense

 Read the 2010 Ballistic Missile Defense Review here 

The United States has pursued some type of defenses against the threat of ballistic missiles for decades, intertwined during the Cold War with nuclear war fighting tactics and strategy. The Cold War missile defense debate naturally focused in large part on the Soviet Union’s vast nuclear arsenal, the size of which could easily overwhelm any defensive system possible then or now. Therefore much of the discussion concerned tactical considerations during a nuclear conflict, such as protecting ICBM fields in order to preserve a counterforce capability or using missile defense to increase an opponent’s attack costs and thereby decreasing their confidence in conducting a successful attack. In this way, defenses were seen by some as enhancing deterrence: demonstrating a willingness to consciously prepare for a nuclear conflict reinforced the credibility of the deterrent threat.

The Strategic Defense Initiative of the 1980s promised a space-based national missile defense to protect the population and ostensibly render nuclear weapons obsolete, but never developed much beyond the planning stages. Shifting threat perceptions since the 1990s, however, have significantly altered the strategic implications of BMD. Unlike the Soviet nuclear arsenal, the near to medium term threat from rogue states and non-state actors are threats against which today’s technology can more plausibly defend. This fact allows BMD to serve a broader range of strategic functions than during the Cold War.

The United States currently fields a network of ground-based radars and space-based sensors to identify and track potential threats, as well as guide interceptor missiles to their targets in all phases of a ballistic missile’s trajectory: boost, ascent, mid-course and terminal. Large ground-based interceptors (GBI) deployed in California and Alaska provides a rudimentary midcourse defense of the US homeland against simple intermediate and long range ballistic missile threats. Aegis ballistic missile defense ships combine a sea-based forward deployable sensor with a command and control platform and the Standard Missile 3 (SM-3) interceptor for midcourse and terminal phase defense of short to intermediate range threats. Theater High Altitude Air Defense (THAAD) is a mobile system capable of handling short to intermediate range threats in their midcourse to terminal phases. The Patriot air and missile defense system utilizes the Patriot Advanced Capability 3 (PAC-3) interceptor to target short range ballistic missiles in their terminal phase. The GBI, SM-3, THAAD and PAC-3 interceptors use “hit to kill” technology, meaning the interceptor is designed to collide with the target and destroy it using its own kinetic energy. Other technologies are still in development.

The Clinton administration, in line with the demands of the ABM treaty, had differentiated between national and theatre missile defenses, moving forward on the latter while researching the possibility of the former.  By dissolving the ABM treaty, the Bush administration also dissolved the conceptual divisions between national and theatre missile defenses, arguing instead for a layered approach that made such a distinction less meaningful. With a rudimentary national missile defense system already in place in the form of midcourse GBIs, the Obama administration appears poised to focus on medium to intermediate range BMD. While this could be seen as reestablishing the national vs. theater distinction, the further development of capabilities able to intercept threats in their ascent and mid-course phase (whether intermediate range or long range missiles) can only enhance national defenses due to its networked character. Systems such as Aegis, that will eventually be able to address short and long range threats, also blur the distinctions between national and theater defenses. Therefore, the logic of a layered defense will likely continue to be appropriate: as today’s intermediate range anti-access threats develop into tomorrow’s long range anti-access threats, the BMD architecture will likely develop correspondingly. In discussing the strategic aspects of BMD here, theater and national defenses will be considered together, though there may be instances where maintaining this distinction is relevant

The Bush administration viewed missile defense as contributing to four broad defense policy goals. These four strategic functions – assure, dissuade, deter and defeat – have, in various guises, been present in missile defense thinking for decades. The 2001 Nuclear Posture Review conceptualized these four functions in this manner (NPR 2002):

  • Assure: “Defenses of the US homeland and protection of forward bases increase the ability of the United States to counteract WMD-backed coercive threats and to use its power projection forces in the defense of allies”
  • Dissuade: “Defenses can make it more arduous and costly for an adversary to compete militarily with or wage war against the United States…missile defenses can have a dissuasive effect on potential adversaries”
  • Deter: “Missile defense of US territory and power projection forces, including US forces abroad, combined with the certainty of US ability to strike in response, can…reinforce the credibility of US guarantees designed to deter attacks on allies and friends”
  • Defeat: “Missile defenses could defeat small-scale missile attacks intended to coerce the United States into abandoning an embattled ally or friend.”

By Michael Mayer