by Robert G. Gard [contact information]
by Kingston Reif [contact information]
Fact Sheet: U.S. Ballistic Missile Defense
Ballistic missiles are powered initially by a rocket, or several rockets in stages. After burn out of the last stage, the missile follows a high-arched, unpowered, parabolic trajectory to the target. They are classified by their maximum ranges:
- Short-range, 1,000 kilometers
- Medium-range, 1,000 to 3,000 kilometers
- Intermediate-range, 3,000 to 5,500 kilometers
- Long-range, or Inter-continental (ICBM), more than 5,500 kilometers
There are three stages, or phases, of the flight paths of ballistic missiles:
- Boost – begins at launch, moving slowly initially, and lasting three to five minutes until the rocket engine or engines stop firing and the missile begins unpowered flight.
- Mid-course – the missile continues to ascend toward its apogee before beginning its descent. The missile’s payload, including the warhead(s) and countermeasures against defenses, is released during this phase. According to recent reports by the Defense Science Board and the National Research Council, payload and countermeasures deployment can be achieved very rapidly after booster burnout, long before the missile reaches apogee. Almost all of the mid-course stage of Intermediate- and long-range missiles is in space, above the earth’s atmosphere, and can last as long as 20 minutes for ICBMs.
- Terminal – begins when the warhead(s) is descending in the earth’s atmosphere, lasting less than a minute for ICBMs, and ends upon impact or detonation.
The U.S. is engaged in a prolonged, highly expensive program to develop a layered complex of weapons programs tied together in an integrated system of systems to defend the U.S. homeland, troops and facilities abroad, and some allies, from attacks by ballistic missiles.
In FY 2013 the Pentagon requested $9.7 billion for missile defense, including $7.8 billion for the Missile Defense Agency (MDA) and $1.9 billion for Army and other service missile defense programs. According to Missile Defense Agency estimates, Congress has appropriated $149.5 billion for the Agency’s programs between FY 1985 and FY 2012.That total does not include service spending on programs such as the Patriot system or the many tens of billions of dollars spent since work on anti-missile systems first began in the 1950’s.
National Missile Defense; the Ground-Based Mid-Course System (GMD)
Since the 1950s, the United States has spent tens of billions of dollars trying to develop an effective defense against ICBMs. The current effort is focused on countering a “limited” attack by a rogue state, with a single or very few missiles during their mid-course flight stage in space. In 2002, President Bush ordered deployment of ground-based interceptors by 2004 to counter an attack by North Korea or Iran in the event they developed ICBMs and targeted them on the U.S. homeland. There now are 30 interceptors deployed: 26 in Alaska and four in California.
Despite an investment of approximately $39 billion on GMD since 1996, it remains a troubled system. For example:
- A 2012 report by the National Research Council stated: "The current GMD system has serious shortcomings, and provides at best a limited, initial defense against a relatively primitive threat.”
- GMD has a record of testing failures. There have been only eight hits out of 17 tries of the system since 1997. The last two intercept flight tests in January 2010 and December 2010 failed. There has not been a successful GMD flight intercept test since December 2008.
- An operationally configured interceptor has yet to be tested against a target with ICBM range and speed, and there are no near term plans to do so.
- According to Missile Defense Agency Director Gen. Patrick O’Reilly, the interceptors currently fielded in Alaska and California are “more akin to prototypes than production representative missiles in the field.”
- The new Capability Enhancement II (CE-II) version of the ground based interceptor, which is currently deployed on ten of the thirty interceptors, has never successfully intercepted a test target.
The GMD system’s biggest Achilles heel is the inability to deal with countermeasures. Several authoritative sources have warned that any country capable of fielding an ICBM can easily employ effective countermeasures to prevent discrimination between warheads and simple decoys or debris in the target complex. A 2011 Defense Science Board report concluded that while “the ability to dependably discriminate reentry vehicles from penetration aids and other objects,” is essential to an effective missile defense system, “discrimination in the exo-atmosphere is still not a completely solved problem.” This has encouraged an effort to develop the capability to intercept hostile ICBMs in their boost and early intercept phases, before their payloads could be released from the missile.
The Kinetic Energy Interceptor, a mobile land- and sea-based weapon, was canceled in 2009 after expenditures of $4.5 billion over eight years because it proved impractical to design a fast enough interceptor to catch up with ballistic missiles during the short duration of the boost phase of their flight. The Airborne Laser program envisioned mounting an array of chemical laser systems aboard modified Boeing 747 cargo aircraft. In addition to serious technical problems with the laser apparatus itself, a basic limitation proved to be the lack of sufficient range of the laser beam; after spending $5.2 billion on the program, the test aircraft was retired.
Defense against Short and Medium Range Ballistic Missiles
The Patriot Advanced Capability (PAC-3), considered an operational terminal defense system, consists of an interceptor fired automatically from a mobile launcher and guided by a radar to direct impact with the incoming weapon. During the invasion of Iraq in 2003, Patriot destroyed several short range Iraqi missiles; but it also shot down two friendly aircraft, killing three airmen.
The Theater High Altitude Area Defense (THAAD) system employs a single rocket booster on a truck-mounted launcher to attack targets in their terminal phase at higher altitudes than the Patriot can reach. Tactical units have been activated slowly beginning in 2008. A longer range, more powerful booster is in development.
The Aegis missile defense system, originally designed to protect naval vessels against aircraft and cruise missiles, evolved with its SM-2 missile to counter short range ballistic missiles in their terminal phase of flight. The SM-3, Block IA, missile is a three-stage interceptor employing hit-to-kill technology to attack short and medium range ballistic missiles during the mid-course stage of their flight. By mid-2012, five cruisers and 19 destroyers had been outfitted with the Aegis missile defense system, with five additional ships programmed by the end of the year.
The Phased Adaptive Approach (EPAA)
Lt. General Robert G. Gard, Jr. (USA, ret.) is Chairman of the Center for Arms Control and Non-Proliferation where his work focuses on nuclear nonproliferation, missile defense, Iraq, Afghanistan, military policy, nuclear terrorism, and related national security issues. Gard has written for well-known periodicals that focus on military and international affairs and lectured widely at U.S. and international universities and academic conferences.
Kingston Reif is the Director of Nuclear Non-Proliferation at the Center for Arms Control and Non-Proliferation, where his work focuses on arms control, nuclear nonproliferation, nuclear weapons, and preventing nuclear terrorism. He has published letters and articles on nuclear weapons policy in such venues as the Washington Post, Washington Times, Wall Street Journal, Survival, Defense News, and Bulletin of the Atomic Scientists.