The Strategic Defense Initiative: Definition & Organization

Instructor: Jason Waguespack

Jason has taught Political Science courses for college. He has a doctorate in Political Science.

In this lesson, you will learn about the proposed Strategic Defense Initiative, a Cold War-era program designed to defend the U.S. against a Soviet nuclear attack, as well as the controversy over it and the program's eventual fate.


A constant worry for the United States during the Cold War was how to stave off a possible Soviet nuclear strike. Only the threat of 'Mutual Assured Destruction,' or MAD, the possibility that the Soviets could be destroyed by American nuclear missiles if the Soviets launched missiles at the U.S., seemed to keep the Soviets from launching a strike. The two countries were trapped in a stand-off with two giant guns pointed at each nation's head, with each hoping the other didn't pull the trigger.

President Reagan Addresses the Nation on SDI
Reagan Addresses the Nation on SDI

In the early 1980s, President Ronald Reagan's military and scientific advisors presented him with a proposal to create a system to shield the United States from incoming nuclear missiles. Reagan decided that a defense against a nuclear attack was preferable to relying on MAD to defer nuclear war. On March 23, 1983, President Reagan addressed the nation. He argued it would be better to save lives than to have to avenge them in a nuclear war. To that end, he laid out a proposal for a defense system that would intercept and destroy Soviet missiles in the air before they reached American soil. Though this new system would likely take decades to achieve and suffer setbacks before it could be realized, Reagan argued the price was worth it if it could render nuclear weapons obsolete. He called this defense system the Strategic Defense Initiative.

Organization of SDI

A Missile Interceptor
missile interceptor

The goal of the Strategic Defense Initiative, or SDI as it is commonly known, was to defend the United States from incoming nuclear missiles by a combination of land and space-based weapons. Sensors at battle stations placed on land or in space would detect Soviet missiles when launched. These stations would then target the missiles while they were still in flight and destroy them with laser beams. Also, missiles placed on air platforms as well as missiles on the ground would form another layer of defense by intercepting and destroying Soviet missiles. Many of these missiles would defend major American targets such as missile silos from Soviet attack.

Controversy over SDI

SDI Logo
SDI logo

The Strategic Defense Initiative met with fierce political scrutiny. The weapons proposed, including laser beams and neutron particle beams, were considered technologies that were too advanced and unproven to invest in. The outlandish laser weapons, along with the fact that some of the weapons were to be put in space, caused critics to dub the program 'Star Wars' after the title of the famous blockbuster science fiction film. Critics also argued that SDI would take the arms race into outer space, with the Soviets placing their own weapons in space to keep up with the Americans. SDI detractors also claimed the Soviet Union would expand its offensive nuclear capacity to try and overcome a possible American defense shield. Still, Reagan prevailed on Congress to fund SDI, and by 1987 annual spending on SDI had reached an excess of $3 billion.

In spite of the criticism that SDI couldn't work, the Russians took the program seriously and publicly opposed its creation. Soviet leader Mikhail Gorbachev even asked Reagan to drop the program at the 1986 summit in Reykjavík, Iceland, in exchange for disarmament concessions. Reagan refused, continuing to pursue the program through the end of his presidency.

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