Ballistic Missile Defense and the Strategic Defense Initiative

by Wm. Robert Johnston
last updated 15 January 2002

Ballistic missile defense (BMD) means any form of defense against ballistic missiles. Ballistic missiles use one or more stages to launch their warhead(s) into ballistic, projectile motion towards targets. They include short range missiles like Scuds and ICBMs like the U.S. and Russia have. In contrast, cruise missiles fly through the atmosphere like miniature airplanes.

In the late 1950s, both the United States and Soviet Union began deploying ballistic missiles armed with thermonuclear warheads. These included ICBMs, intercontinental ballistic missiles, launched from land, and SLBMs, submarine-launched ballistic missiles. The U.S. and Soviet Union began to develop ABMs (anti-ballistic missiles) to defend against missile attack in the late 1960s, but in 1972 the two nations signed the ABM treaty which limited both sides to two defensive missile sites. The treaty was soon amended to limit each side to one defensive missile site. The U.S. dismantled its one site, in North Dakota, in 1975 (only months after it was completed). In contrast, the Soviet Union had completed defensive missile sites around Moscow in 1968 and began modernizing them in 1980.

The Strategic Defense Initiative, or SDI, was a United States research and development program to develop a national BMD system, or a system to defend against nuclear ballistic missile attack, from 1983 to 1993. In March 1983, President Ronald Reagan made a speech calling for a program to research the feasibility of deploying a system for defending the entire nation against nuclear attack. Political opponents were quick to criticize the proposal and labeled it "Star Wars."

By then, both the U.S. and U.S.S.R. had large numbers of ICBM and SLBM missiles which would launch nuclear warheads to travel through space to reach the other country, taking 10-30 minutes to reach their targets. SDI was planning to produce a "layered" defense, with different weapon systems continuously attacking Soviet warheads from launch to impact, including some systems based in space. Development and deployment of a defensive system was envisioned in two phases. In Phase 1 electromagnetic rail guns and homing interceptors in space along with missiles on the ground would be used to attack incoming warheads. Phase 2 would use advanced weapons such as space-based and ground-based lasers, particle beam weapons, and possibly nuclear x-ray lasers, all under control of a system of supercomputers. These would be supported by systems of satellites and ground-based systems to detect and target Soviet missiles and warheads.

After Reagan's speech, the Strategic Defense Initiative Organization (SDIO) was formed to coordinate the program. In June 1984 the Air Force conducted a successful test in which an interceptor homed in on and collided with an incoming test missile warhead, destroying it. In 1988 a researcher proposed "Brilliant Pebbles," an interim system of low-cost space-based interceptors that would not need centralized computer control to destroy enemy missiles. Some SDI technology was used by Patriot missile systems in the 1991 Persian Gulf war to defend against Iraqi Scud missile attack, although success was limited because the Patriot system was originally designed for defense against aircraft, not missiles.

Costs of an SDI system were estimated at $100 billion or more. Opponents used this to try to stop SDI, although this cost would have been a small fraction of the Defense Dept. budget. From 1984 to 1993 a total of $39.7 billion was spent on the program.

SDI was consistently opposed by many, including Democrats in Congress. Criticisms included: the high cost; supposedly insurmountable technological challenges; the fact that the U.S. would have to withdraw from the 1972 ABM treaty to deploy a system; Soviet claims that the weapons could be used offensively; methods by which the Soviets could allegedly outwit a system; and others. These charges were addressed by researchers, who demonstrated ways to overcome the technological challenges and Soviet countermeasures, for example. SDI supporters also promoted the moral and legal superiority of defense. They argued that destroying an enemy attack before it killed millions was better than allowing the attack to happen, and then retaliating by killing millions in the enemy country. Nontheless, the news media consistently carried a one-sided opposing viewpoint. The research program was hampered by political opposition. Research was conducted, but no defense was ever built.

When the Soviet Union collapsed in 1991 (in part due to the expense of trying to compete with the SDI program) and the Cold War ended, opponents pressed for an end to the program. President Bush proposed a system called Global Protection Against Limited Strikes (GPALS). After Clinton became president in 1993, the new administration quickly demoted SDI and cancelled GPALS. In May 1993 the SDIO was replaced by the Ballistic Missile Defense Organization (BMDO) with a lower budget ($3.8 billion in FY 1994 down to $2.8 billion in FY 1997) and limited to developing ground-based defense systems.

Interest in ballistic missile defense continued after the Soviet Union collapsed. Concerns remain about accidental or unauthorized missile launches from Russia, and hostile third world nations are increasingly gaining missiles of their own. After Republicans gained a majority in Congress in 1996, Congress voted six times for the United States to deploy a defense against at least a small number of enemy missiles. President Clinton vetoed these acts five times. However, in August 1998 North Korea tested a ballistic missile which landed near Alaska--years earlier than Clinton administration predictions--and Clinton finally signed the National Missile Defense Act of 1999 in March 1999. Nonetheless, the Clinton administration's support remained weak.

At this time, battlefield and ship-based anti-missile systems are close to providing some degree of protection against tactical and theater ballistic missiles. A near-term limited national missile defense would most likely use land-based conventional ABMs. The only boost-phase weapon currently in advanced development is the Air-Borne Laser (ABL); this as well as space-based lasers are currently cited as potential weapons.

In May 2001, President George W. Bush called for pursuit of a national missile defense to counter limited attacks. He also called for an eventual end to the ABM treaty, potentially allowing the U.S. to rely on defense rather than offense for security. (The proposal was, of course, promptly criticized by the People's Republic of China, Russia, and the Democratic Party.)

During the remainder of 2001, the U.S. conducted two tests of interceptors for a ground-based system, both successful. In December 2001, the Bush administration notified Russia that the U.S. was giving its six months notice of withdrawal from the ABM treaty. Plans are being considered for constructing a first ABM site in Alaska.

© 1999-2001, 2002 by Wm. Robert Johnston.
Last modified 15 January 2002.
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