The Strategic Defense Initiative, or “Star Wars,” is over thirty years old. SDI has never, despite the intentions of several presidents, provided the United States with an effective, reliable defense against the ballistic missiles of an opponent of the scale of the Soviet Union. Nevertheless, the inauguration of the SDI project marks a crucial inflection point in the history of missile defense in the United States.

But appreciating the break that Star Wars represented requires an understanding of what went before. Ronald Reagan didn’t start the national conversation on missile defense, but he did revive it, and that revival has set the terms for the debate ever since.

The Phantom Menace: Missile Defense Before Star Wars

Shortly after German V-2s began raining down on England, the United States Army started thinking about ways to defeat the missiles. V-1 “buzz bombs” were easy; they were simply unmanned aircraft that flew on predetermined flight paths, and that could be shot down with traditional means. V-2s posed a much more difficult problem, as they moved too fast to shoot down with anything but the wildest stroke of luck.

Army efforts went hand-in-hand with the project of developing surface-to-air missiles that could reliably kill enemy aircraft. The problems associated with anti-ballistic missiles (ABMs) and surface-to-air missiles (SAMs) were in many ways similar, but the latter proved far easier than the former. In simple terms (as described by Ernest Yanarella), the problem of missile defense involved detection of launch, tracking of missile, discrimination between missile and decoy, vectoring of interceptor and destruction of target missile. Each of these five presented complex problems that bedeviled engineers in the 1950s, and have continued to bedevil them today.

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In the 1950s, the ABM project led to bitter interservice squabbles, as the Army tried to find itself a strategic role. The roles and missions of the Army and Air Force changed several times over the course of the decade, as responsibilities for ballistic-missile and SAM development shifted between the services. The Navy, content with developing its own ship-borne SAM systems, stood aside.

The Army opened the 1960s by trying to assert its strategic relevance with the Nike-Zeus ABM system. The Air Force favored investment in offensive systems, and Secretary of Defense Robert McNamara was unconvinced. In 1962, the Department of Defense killed Nike-Zeus, arguing that although it could intercept some ballistic missiles, it did not provide a practical, affordable defense. The Army struggled on for several years with the Nike-X, Sentinel, and Safeguard systems, but never convinced McNamara or the other services of the practicability of the project.

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For their part, the Soviets sought a system that could defeat both NATO and Chinese missiles. Soviet paranoia about the potential for a decapitation strike against the Kremlin made missile-defense development a priority, especially given the sophistication of American submarines and the proximity of NATO intermediate-range ballistic missiles. Soviet developments provided grist for ABM supporters in the United States, but also demonstrated the ease with which a determined attacker could overwhelm and destroy even a significant ABM system.

Fortunately, both the Soviets and the Americans eventually recognized the destabilizing effects of defense systems that could undercut two legs of the nuclear triad. In the United States, McNamara provided one of the strongest institutional voices against strategic missile defense, arguing that it would inevitably amplify the expensive, destabilizing arms race between the United States and the USSR. The 1972 ABM Treaty sharply limited the extent to which either side could develop national ballistic-missile defenses, even as it left some latitude for regional protection (a clause insisted upon by the Soviets). The ABM Treaty didn’t end research on the American side, but it did suggest to the services that investing prestige and resources in missile defense wouldn’t prove a big bureaucratic winner.

A New Hope: Ronald Reagan and the Strategic Defense Initiative

In March 1983, President Ronald Reagan jump-started ABM research by proposing the Strategic Defense Initiative, a cluster of ground- and space-based systems that promised to defeat a Soviet ballistic-missile attack on the United States. Reagan was suspicious of bilateral efforts at arms limitation, and sought to leverage U.S. technological and economic advantages. Reagan also detested the reliance of the United States on the logic of mutual assured destruction.

Reagan’s pursuit of missile defense quickly acquired the name “Star Wars,” simultaneously impressive and derisive. On the impressive side, the Reagan administration plans envisioned a technologically innovative system, stationed partially in space, that could defeat even a massive, strategic Soviet assault. This system went through several design iterations, but included ground-based interceptors, a variety of lasers, and a system of space-based kinetic devices (which would eventually acquire the name “Brilliant Pebbles”) designed to destroy Soviet missiles in flight.

On the derisive side, the envisioned systems were enormously expensive, and perfecting them would seem to require decades of dedicated investment, research and engineering. Moreover, even a perfect system could not hope to stop Soviet bombers or cruise missiles from threatening U.S. targets, nor prevent the use of the USSR’s massive arsenal of tactical nuclear weapons against NATO.

Also in the 1980s, it became apparent that the Warsaw Pact could open a conventional war with a series of conventional ballistic-missile strikes against key NATO military infrastructure in Europe. Even without nuclear weapons, hyperaccurate Soviet missiles could dismantle NATO’s conventional defense strategy. This enhanced the need for theater ballistic-missile defense, apart from the more ambitious strategic system, and speeded upgrades to the Army’s Patriot surface-to-air missile system. The full effect of these upgrades took some time to work out (the Patriots turned in service of limited effect in the Gulf War), but eventually produced a very effective theater defense.

Opinions differ with respect to the political impact of missile defense on the USSR. To give only some very recent examples, Ken Adelman has argued that Soviet concern over Star Wars drove Gorbachev’s willingness to embark on significant nuclear cuts in the 1980s. However, Michael Krepon argues that the reductions, in fact, represented Gorbachev’s strategy for undercutting Star Wars; if tensions declined, Congress would never accept Reagan’s demands for huge outlays on unproven tech. In any case, the collapse of the Soviet Union stemmed from too many factors (internal economic collapse, growing NATO conventional power, the exhaustive war in Afghanistan, the nationalities problem) to definitively claim an important role for SDI. Unquestionably, however, the collapse of the Soviet Union undercut the willingness of the United States to shell out for missile defense, and many of the major programs associated with the project were cancelled in the 1990s.

The Force Awakens: The Long-Term Fallout of SDI

The technologies that enable missile defense (communications, surveillance, high-speed computing) have improved remarkably since the 1980s, even as concern over global thermonuclear war has declined. The most effective modern missile defenses have evolved from tactical, sea-based systems; Japan, South Korea and the United States all now sport Aegis-based missile-defense systems from cruisers and destroyers, and ballistic-missile defense is fast becoming a core U.S. Navy mission. For its part, the Army operates the Patriot point defense systems and the closely related THAAD (Terminal High Altitude Area Defense) system. The Army also operates the Ground-Based Midcourse Defense systems in Alaska and California. Together, these systems provide some defense against a piecemeal ballistic-missile attack launched from a small, unsophisticated opponent.

SDI surely did help facilitate advances in communications, sensor and computing technology, but those advances have been outpaced by improvements in civilian technology that have already found their way into the military sphere. Nevertheless, pouring billions in government dollars into research and development undoubtedly pushed the technological envelope forward, even if the specific gains are hard to measure.

The successors to the Strategic Defense Initiative have created their own political problems. In 2002, the Bush administration withdrew from the ABM Treaty in order to more vigorously pursue the dream of national missile defense. This deeply irritated the Russians, who have since justified the modernization of their strategic delivery systems on the basis of U.S. threat. The U.S. promise to deploy interceptors and tracking systems to Poland and the Czech Republic only exacerbated this tension. For its part, the People’s Republic of China has also argued that the development of U.S. missile defense justifies the decision to modernize and enlarge its ballistic-missile arsenal.

On the domestic side, missile defense has remained part of every Republican platform since the 1980s. The latest iteration reads: “We will accept no arms-control agreement that limits our right to self-defense; and we will fully deploy a missile-defense shield for the people of the United States and for our allies.” Republican presidential candidates have consistently attacked their Democratic rivals for being insufficiently enthusiastic about missile defense; Bob Dole accused Bill Clinton of leaving the United States unprotected against threats from terrorists and rogue states, just as Mitt Romney condemned Barack Obama for failing to pursue a missile-defense system in Eastern Europe with sufficient vigor. Whether these attacks have found blood is a different question, but since Reagan, Republicans have regularly relied on support of missile defense to demonstrate toughness to the voting public.