From the Publisher

When President Bush fulfills his campaign plege to pursue a national missile defense (NMD), as he almost surely will do, the decision will have potentially seismic consequences for American national security and international affairs. Most countries, including many of America's closest allies, warn that missile defense will trigger an arms race and jeopardize three decades of arms control efforts.

Within the United States, reactions to national missile defense have broken down along well-worn lines. Opponents, most of whom are Democrats, complain that the benefits of national missile defense are uncertain and the budgetary and strategic costs are steep. Supporters, most of whom are Republicans, insist that the United States not only should build defenses, but must, because hostile countries are gaining long-range ballistic missiles.

Both sides make valid points. But the current debate over missile defense has degenerated into a dialogue of the deaf. Each side repeats its claims with evangelical fervor, often exaggerating the harm or promise of missile defense.

In Defending America, James M. Lindsay and Michael E. O'Hanlon provide a balanced, nonpartisan analysis of missile defense that makes three broad points. First, the threat of long-range missile proliferation, though limited to a few countries, is nonetheless real. Second, defensive technologies are improving. Defense against large-scale attacks remains a dream, but the prospects are good that the Pentagon will be able to develop an effective defense against small missile attacks by relatively unsophisticated foes over the next decade. Third, attempting to build a large-scale missile defense will threaten Russian and Chinese strategic interests and likely provoke Moscow and Beijing into retaliating in ways that will ultimately make America less, rather than more, secure.

Lindsay and O'Hanlon conclude that the best way to promote American security is to build a limited, two-tier defense that targets the potential new ballistic missile powers. The first tier would consist of a modest number of boost-phase interceptors, based near threatening countries. The second tier would be a smaller version of the system the Clinton administration proposed to build, but based in North Dakota rather than Alaska. Since the construction season is substantially longer in North Dakota than Alaska, this approach would lessen the pressore to begin construction in the immediate future, before the necessary technological and diplomatic groundwork has been laid. This two-tier system is fully compatible with making deep cuts in the stockpiles of both U.S. and Russian nuclear weapons.

Lindsay and O'Hanlon recommend that the Bush administration work hard to persuade Russia to modify the Anti-Ballistic Missile (ABM) Treaty to permit the deployment of a limited missile defense. But they maintain that the United States should deploy its missile defense even if Russia ultimately refuses to give its assent. They further argue that any successful NMD deployment will require thorough discussions with China.

The authors warn that moving precipitously toward deployment, or deploying the wrong kind of system, could do more harm than good. The danger is not a new arms race, but that Russia and China will respond with policies that discourage arms reductions and encourage proliferation. Defending America cautions President Bush to proceed carefully in his choices of technology, timing, and diplomacy. Otherwise, building an NMD system could be worse than having no system at all.

Publishers Weekly

In a potential blueprint for President George W. Bush's defense team, the authors construct an argument for a limited missile defense system. Such a shield has hovered over U.S. political discourse since Ronald Reagan proposed Star Wars in 1983, but the authors, senior fellows at the Brookings Institution, note that Lyndon B. Johnson first raised the idea in 1967. Lindsay (Congress and Nuclear Weapons), formerly of the National Security Council (during Clinton's presidency), and O'Hanlon (Technological Change and the Future of Warfare), who teaches at Columbia and Georgetown and has worked for the Congressional Budget Office, weigh three possibilities: a complete shield, as proposed by Reagan; no shield; and the limited one they favor. Their plan includes interceptors to shoot down missiles early in their flight, and midcourse interceptors like those President Clinton proposed. They admit their proposal's weaknesses including possible negative reactions from Russia and China but ultimately decide that such a system is both feasible and secure enough to defend the U.S. against attacks from "rogue nations" such as Iraq, Iran and North Korea. "The fact the United States cannot defend itself perfectly against every threat is no reason to give up the effort," Lindsay and O'Hanlon assert. They include appendixes of past weapons treaties and U.S. intelligence estimates of threats posed by other nations. Policy wonks will devour this thorough, academic book; other readers seeking a conservative, interventionist treatment of a hot topic will also benefit. (May) Forecast: A dry, rigorous study, this has narrow appeal, but will receive attention and trickle down into public debate. Copyright 2001 Cahners Business Information.

Library Journal

The major controversial defense issue for the new Bush administration is the development of a national missile defense system, popularly known as the "Star Wars" defense during the Reagan administration. The authors, who are senior fellows in Foreign Policy Studies at the Brookings Institution, favor a smaller system that might not be as threatening to China and Russia. They discuss the concepts of defending America, the threats it faces, and system programs and architectures. The complicated and expensive technical and political issues that need to be solved before the system can be deployed are analyzed and courses of action proposed. At the end, one can find the texts of treaties, joint agreements, and official statements. The main points of this study are also summarized in the Brookings Policy Brief of the same title (www.brookings.edu). The authors convincingly show that the diplomatic costs really do restrict America to a limited missile defense. This well-argued work should go on the shelf next to James J. Wirtz and Jeffrey A. Larsen's Rocket's Red Glare: Missile Defenses and the Future of World Politics (Westview, 2001) and Roger Handberg's Ballistic Missile Defense and the Future of American Security (Praeger, 2001). Daniel K. Blewett, Coll. of DuPage Lib., Glen Ellyn, IL Copyright 2001 Cahners Business Information.

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Defending America
The Case for Limited National Missile Defense

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By James M. Lindsay and Michael E. O'Hanlon

Brookings Institution Press

Copyright © 2001 The Brookings Institution.
All rights reserved.
ISBN: 0815700083

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Chapter One

Should the United States build a national missile defense (NMD) to protect the American people, and possibly key allies as well, against attack by long-range ballistic missiles? President Bill Clinton's September 2000 announcement that he was deferring the decision on whether to deploy an NMD system puts this question squarely on the Bush administration's agenda. The United States currently has no nationwide defense against missile attack. Should President Bush fulfill his campaign pledge to "build effective missile defenses, based on the best available options, at the earliest possible date," the decision will have potentially seismic consequences for both American national security and international affairs. Most countries, including many of America's closest allies, warn that missile defense will trigger an arms race and jeopardize three decades of arms control efforts.

    Within the United States, reactions to national missile defense have broken down along well-worn lines. Opponents, most of whom are Democrats, complain that the benefits of national missile defense are uncertain and the costs steep. They argue that effective missile defenses are difficult to build—not the least because America's adversaries have every incentive to find ways to defeat them—and that the investment of billions would produce only a high-tech sieve. At the same time, deploying an NMD system would strain relations with Russia, China, and Europe and threaten three decades of arms control. Even those who believe that formal superpower nuclear arms control has become anachronistic should worry. A hasty, ambitious NMD deployment could worsen U.S. security by impeding cooperative programs to secure Russia's nuclear weapons and materials, and by reducing the odds that Moscow and Beijing will tighten their controls over the proliferation of weapons of mass destruction. The result may well be a world with more intercontinental ballistic missiles (ICBMs) and weapons of mass destruction that would leave America less secure, not more secure.

    Supporters of national missile defense, most of whom are Republicans, insist not only that the United States should build defenses but that it must. They argue that revolutionary developments in radar, laser, and data processing technology are transforming missile defense from the stuff of science fiction into a here and now reality. These technological breakthroughs come as nuclear and ballistic missile technology is spreading to states that are virulently hostile to American power and values. According to this view, a national security policy that deliberately leaves the American people vulnerable to attack when technology makes it possible to protect them is immoral and unacceptable. Not only does it fly in the face of common sense to leave the nation undefended, but it could hamstring America's role in the world. If hostile countries such as Iraq felt they could threaten the United States, and thereby deter it from defending its allies and global interests, these countries might feel less constrained about threatening or attacking their neighbors. Moreover, vulnerability to long-range ballistic missile attacks could cause America's friends and allies to doubt its willingness to stand by its security commitments, thereby weakening support for the United States around the world.

    Both sides in the NMD debate make valid points. But rather than generating a serious discussion of how each side's legitimate concerns can be forged into a sensible policy for the country, the current debate has degenerated into a dialogue of the deaf. Each side repeats its claims with evangelical fervor, often exaggerating the harm or promise of missile defense. National missile defense, however, should not be an ideological issue to champion passionately or oppose resolutely. The issues are complicated, not clear cut. What is needed is not partisan or ideological cheerleading but a sober analysis of the role national missile defense can play in American national security. That is what this book seeks to provide.

Déjà Vu All Over Again?

Whether to defend the United States against ballistic missile attacks is not new to American politics. The current debate over national missile defense marks the third round in a decades-long debate over the merits of defense in the nuclear age.

    Although initial research programs had begun a decade earlier, the first major missile defense debate began in 1967 when the Johnson administration proposed building the Sentinel system, which would have placed nuclear-tipped interceptor missiles at fifteen sites around the country, including ten near major metropolitan areas. People living near the planned sites rebelled, however, because they feared that putting the missiles in their backyard would greatly increase their chances of becoming the target of an attack. The Nixon administration recognized that Sentinel was politically unsustainable and changed course. It abandoned the idea of defending American cities and proposed instead to use the same interceptor technology to defend a portion of America's land-based ICBMs. The new program, named Safeguard, proved politically controversial as well, and it barely survived congressional opposition led by a coalition of Democrats and liberal Republicans. In October 1975 the lone Safeguard site opened in Grand Forks, North Dakota. Less than two months later, however, anti-Safeguard forces prevailed on Capitol Hill, and Congress voted to close the base, effectively writing off an investment of more than $20 billion (in 2001 dollars).

    With the passing of Safeguard, missile defense disappeared as a political issue until Ronald Reagan resurrected it in his famed 1983 "Star Wars" speech. The result was a new, high-profile program, the Strategic Defense Initiative (SDI), that sought to defend the United States with ground-based and space-based weapons. Like Sentinel and Safeguard, SDI polarized Congress, though this time largely along party lines. Proponents (mostly Republicans) argued that defending America was a moral imperative; critics (mostly Democrats) argued that it was wasteful and dangerous. Unlike Safeguard, however, SDI never left the research and development stage. The Bush administration reduced the program's political profile and focused it on long-term research. The Clinton administration initially went even further. At the behest of many in the military, it redirected spending away from national defenses and toward theater missile defenses (TMD) designed to protect U.S. troops and allies against attacks by shorter-range missiles like the infamous Scud that played such a prominent role in the 1991 Persian Gulf War (figure 1-1). In contrast to NMD programs, TMD programs have enjoyed widespread political support during the past decade because the threat of attack on U.S. troops from shorter-range missiles has been judged considerable and because TMD systems are usually not seen as threatening the deterrents of other major nuclear powers.

    The Sentinel, Safeguard, and SDI programs all foundered on two obstacles. The first was technological—none of the three programs offered the prospect of an effective defense. The Johnson administration acknowledged from the start that Sentinel could not defend the United States against a Soviet attack—the system was justified as a "thin" defense against a possible Chinese attack. (China did not deploy long-range missiles capable of reaching U.S. soil until 1980.) Even in that limited role it raised major worries because it sought to destroy incoming warheads in their terminal phase by detonating nuclear warheads in the atmosphere over the United States. The Safeguard system's interceptor missile flunked nearly half of its flight tests. Even if the interceptor missile had worked flawlessly, the Soviet Union could easily have overwhelmed the lone Safeguard site (which is why the Ford administration acquiesced in the congressional decision to shut it down). The SDI proponents insisted that the United States was on the verge of mastering exotic technologies such as x-ray lasers. By the end of the Bush administration, however, the Pentagon had concluded that such weapons were decades away from being ready.

    The second, and in many ways more important, obstacle to missile defense was strategic. Critics argued that even if highly effective defenses could be built, they would—at least in the context of the U.S.-Soviet rivalry—produce a more dangerous world, not a less dangerous one. One problem is that they would have likely fueled a superpower arms race. Moscow would build more offensive weapons in order to be certain it could overwhelm any U.S. defense, and Washington would respond similarly to any Soviet defense. Worse yet, defenses might have made war more likely. Both countries would fear that the other side could attack first and then use its defenses to blunt a retaliatory attack. This would have created an incentive to strike first, before the adversary could attack. Moreover, the incentive to "use them or lose them" would be strongest at the worst possible time—during a crisis. Finally, given the state of technology, defenses would probably not have worked in any case—especially in light of the enormous strategic arsenals each side wielded against the other.

    The conviction that national missile defenses fuel arms races and make crises more dangerous led the United States and the Soviet Union to sign the Anti-Ballistic Missile (ABM) Treaty in 1972. The treaty flatly banned all forms of national missile defense that could provide territorial defense for the United States or Soviet Union against long-range missile attack. It did not, however, ban defenses against strategic or long-range missiles outright. Instead, it permitted both countries to operate two small missile defense systems (like Safeguard), one around its national capital and the other around an ICBM site, each equipped with no more than one hundred interceptors designed for local defense. (In 1974 the United States and the Soviet Union agreed to cut the number of permitted sites and interceptors in half; Russia continues to maintain its site around Moscow.) The treaty permitted a certain amount of radar capability for each defense site; it also permitted early-warning radars along each country's periphery and facing outward (and in certain overseas locations) as well as satellites for similar purposes. But to create firebreaks against any rapid or clandestine expansion of these limited defenses, the treaty barred other types of sensors, the development and testing of sea- and space-based defenses, as well as other mobile national missile defense systems. It also banned exports of long-range missile defense technologies. Both countries retained the right, however, to develop and build theater defenses, conduct basic research on virtually all missile defense technology, and develop and test fixed land-based ABM technologies as long as any deployments met the treaty's strict guidelines.

    In sum, the core motivation behind the ABM Treaty was that neither country should develop a strategically significant defense, that is, one that could render the adversary vulnerable to a disarming first strike, or spark an arms race. However, the letter of the treaty bans all national missile defenses—that is, any system, however limited in scale, that could defend all of a country's territory against long-range missile attack.

    In signing the ABM Treaty, Washington and Moscow formally embraced the idea that, at least in the case of their superpower rivalry, mutual vulnerability helped prevent nuclear war and dampen a wasteful arms race. (The two sides were not so enamored with vulnerability that they agreed to restrict air defenses or antisubmarine warfare capabilities.) The wisdom of this decision has been debated ever since; indeed, it was hotly debated during the 1980s, when the cold war continued. Missile defense critics acknowledge that the logic of mutual assured destruction (MAD) is counterintuitive, but they insist it forms the cornerstone of strategic stability. Many NMD proponents, however, reject the idea that a MAD world has an overriding virtue. They argue that any policy that leaves the United States vulnerable to a nuclear attack, whether accidental or intentional, is immoral. What is often overlooked amid this sparring is another, more nuanced, possibility: a limited defense against small powers may have virtue even if there is no alternative to a MAD world between the great powers.

Is the Third Time a Charm?

Has anything changed since the Sentinel, Safeguard and SDI debates to warrant rethinking the idea of national missile defense? Proponents say yes. They make three points. First, U.S.-Russian relations have improved greatly with the end of the cold war, easing fears that defensive deployments will inevitably spark an offensive arms race. The warmer strategic climate also has lowered the bar for judging any missile defense worthwhile. A missile defense that would have been pointless during the cold war given the size of the Soviet threat may make sense today (table 1-1). Second, the United States faces a greater threat of attack as missile technology spreads to more countries. Many of these new ballistic missile powers are deeply hostile to American values and interests. Third, technology has improved, making it possible to build effective defenses against the smaller threats that the new ballistic missile powers pose.

    There is more truth to each of these claims than critics are willing to acknowledge. The changes are not as dramatic, however, as missile defense proponents would have it.

Table 1-1. Evolution of U.S. National Missile Defense Programs
Item	Mission	Threat size	Space-based laser	Space-based interceptors	Ground-based interceptors
Strategic Defense     Initiative (1980s)	Counter massive Soviet     ballistic missile strike	1,000s	10s	4,000	1,500
GPALS (early 1990s)	Defeat accidental or     unauthorized ballistic     missile launch	200	No	1,000	750
Limited national missile     defense (2000)	Defend against very small     rogue state threat	A few to a few 10s	No	No	100 to 250
Source: Walter Slocombe, undersecretary of defense (policy), "U.S. Limited National Missile Defense Program," presented at Harvard-CSIS Ballistic Missile Defense Conference, Cambridge, Mass., May 2000.

    Better Relations with Russia (Though Don't Forget about China)

    With the end of the cold war, the United States and Russia are no longer enemies and have begun to take important steps to reduce the threat they pose to each other. They no longer deploy huge land armies against each other. They have negotiated the Strategic Arms Reduction agreements (START I and START II), which if implemented will bring the number of strategic nuclear warheads on each side down to 3,000-3,500. They are committed to using the START III negotiations to cut their arsenals to no more than 2,000-2,500 strategic warheads apiece. Under the Department of Defense (DoD) Nunn-Lugar cooperative threat reduction initiative and related Department of Energy (DOE) programs, American scientists visit Russian nuclear weapons labs and vice versa, U.S. technology helps protect Russian weapons and nuclear materials from theft and diversion, and American dollars pay for the partial dismantlement of an aging Russian nuclear arsenal.

    The fundamental transformation in U.S.-Russian relations clearly creates the opportunity for new discussions on missile defense, as Moscow itself acknowledges. In 1997, then-Russian president Boris Yeltsin agreed to consider Bill Clinton's request to negotiate changes to the ABM Treaty to permit the deployment of a limited national missile defense. In 2000, the new Russian president, Vladimir Putin, acknowledged that missile defenses have a role to play in the post-cold war world and proposed that Russia and NATO work jointly to develop them.

    But claims about a new strategic climate are easily pushed too far. Although Russia and the United States have better relations, they are not allies. Substantial suspicion still marks the relationship—witness the tensions over NATO's 1999 war against Serbia and Russia's ongoing war against Chechen rebels. The distrust is especially strong in Moscow. It understandably fears defenses that theoretically could some day render its nuclear deterrent obsolete and further diminish its already sinking international status. So Washington should not be surprised that Moscow does not enthusiastically embrace its missile defense proposals.

    The focus on how much warmer U.S.-Russian relations are than U.S.-Soviet relations also overlooks another key player in the missile defense debate: China. Unlike Russia, China is not a declining power but a rising one; and again, unlike Russia, China has specific territorial issues (notably Taiwan) over which it could conceivably wage a war with the United States. How does the missile defense debate look in Beijing, then?

    China is not a signatory to the ABM Treaty, but missile defense clearly affects its interests. With only about twenty ICBMs in its arsenal, China has never had a robust second-strike capability against the United States. Deployment of even a "limited" NMD system could, depending on the specific architecture chosen, make the value of its nuclear deterrent even more questionable. Missile defense looks especially threatening to Beijing coming as it does on the heels of a decade of seemingly closer U.S. support for Taiwan—a rogue, breakaway province in China's eyes—as well as a 1997 White House decision to add Chinese political and military installations back into U.S. strategic nuclear targeting plans after a twenty-year absence. No one should be surprised, then, that Beijing looks skeptically on President George W. Bush's claim that "America's development of defenses is a search for security, not a search for advantage."

    It is tempting to dismiss Russia's and China's complaints as their problem. But that view is too simplistic, even from the perspective of enhancing U.S. security. At a minimum, deploying defenses over Russia's objections could jeopardize President Bush's hopes to make deep cuts in offensive nuclear weapons. Until the day that Russia sees the United States as entirely unthreatening—an outcome to be hoped for but not one on the immediate horizon—it will continue to link its offensive deployments to U.S. decisions on missile defense. Fiscal constraints will hamper its ability to do so, but Moscow will still retain some low-cost options for deploying a sizable nuclear arsenal—such as retaining the multiple-warhead ICBMs it is supposed to destroy under START II. Chances are, then, that the more robust the U.S. defense, the larger the Russian nuclear arsenal. The same goes for China.

    Some may say, so what? After all, with the cold war over, superpower arms balances no longer have the importance they once did. And if China builds up its offensive strategic forces to counter a U.S. defense, at least it will have fewer resources to spend on other military instruments—such as the amphibious forces that would be needed to seize Taiwan.

    But the fallout from a push for missile defenses would probably redound to America's disadvantage. Both Russia and China would probably improve their existing countermeasure technologies—particularly against so-called midcourse defenses that attempt to destroy enemy warheads in space—a step that any country with the resources to test missiles repeatedly can probably take with considerable success. If Moscow and Beijing feel threatened by a U.S. missile defense, they might also respond by deploying their nuclear forces on states of hair-trigger alert. (Russia already does so, but future arms control efforts could change that.) This would substantially increase the risk of accidental war, hardly the desired outcome of missile defense.

    Russia might also curtail its cooperation with the United States to secure its nuclear arsenal. Cooperative programs have consolidated and secured most of Russia's nuclear weapons to date, but challenges remain. Surplus nuclear materials that are not inside actual nuclear warheads remain widely dispersed and vulnerable to theft. In addition, large numbers of Russian weapons scientists, many of whom are now working on temporary contracts that reduce their incentives to emigrate to radical states seeking their expertise, do not yet have self-sustaining civilian jobs within Russia.

    Finally, Russia and China might stop cooperating on issues that matter to Washington, particularly nuclear proliferation. Indeed, pursuing national missile defense over Russian and Chinese objections might encourage them to sell technology for developing weapons of mass destruction, building missiles, and defeating defenses to countries such as North Korea, Iran, and Iraq, creating a situation in which the cure aggravates the disease. And China might reduce its efforts to moderate North Korea's behavior, and raise the temperature in its dealings with Taiwan, to complicate U.S. foreign policy and make Washington pay a price for ignoring China's strategic interests.

    To be sure, at this point these worries are hypothetical. No one knows for certain how Russia or China would react to a U.S. NMD deployment that trampled on its interests. However, the vociferousness of Moscow's and Beijing's objections to NMD suggests that their responses would not be benign. So do the normal competitive security dynamics between countries that view each other as rivals. The U.S. National Intelligence Council shares our concerns, concluding, among other things, that Moscow and Beijing may sell countermeasures to other countries if the United States deploys an NMD system. And domestic political pressures may also push Russia and China to react. For example, many Russians view the Nunn-Lugar cooperative threat reduction program as a sophisticated and well-camouflaged U.S. espionage effort. This sentiment has been fueled by a growing irritation with the United States, first because of NATO expansion and then because of the Kosovo war and frequent Western criticisms of the Chechnya conflict. Coupled with an NMD deployment, this irritation could greatly complicate U.S.-Russian relations, possibly undermining cooperation on the Nunn-Lugar or nonproliferation fronts.

    None of this is to gainsay then-governor Bush's claim during the 2000 presidential campaign that "it is possible to build a missile defense, and defuse confrontation with Russia." Both can be done. But it will not be easy. And defenses are not all created equal. Some types will likely intensify confrontation between Moscow and Washington, as well as Beijing and Washington.

    The Spreading Threat

    Missile defense proponents argue that the United States faces a growing ballistic missile threat. Missile defense critics respond by arguing that the long-range ballistic missile threat facing the United States has decreased during the past decade. By some measures the critics are right. During the 1980s, the Soviet Union possessed 2,318 long-range missiles. Today Russia has roughly 1,100, a decline of more than 50 percent. That number will fall further if Washington and Moscow make good on their START III pledge. Meanwhile, no other potential adversaries besides China have built ICBMs, and Beijing's arsenal remains small. And countries such as Argentina, Brazil, Egypt, and South Africa that sought to develop long-range missile technology in the 1980s abandoned their programs in the 1990s.

    These measures, however, ignore the more important trend for the future of American national security: the number of states hostile to the United States and possessing long-range missile technology is likely to grow during the coming decades. The U.S. intelligence community believes that by 2015 the United States will face ICBM threats not just from Russia and China but also from "North Korea, probably from Iran, and possibly from Iraq." Even more troubling, the intelligence community warns that any of these countries may be able to flight test a functioning "ICBM with a reentry vehicle (RV) with little or no warning." So the United States may not have the luxury of waiting for evidence of a clear and present danger before taking steps to counter the missile threat.

    The threat that spreading ballistic missile technology poses, while real, should be kept in perspective. North Korea, Iran, and Iraq may succeed in building ICBMs, but they will not recreate the Soviet missile arsenal. All three countries operate under substantial financial and technological constraints, and according to the U.S. intelligence community, will be able to produce only "a few to tens [of missiles], constrained to smaller payloads, and less reliable than their Russian and Chinese counterparts." Their accuracies may also be poor, and their warheads may or may not survive the descent to earth given the difficulty of building heat-resistant reentry vehicles. All three countries will be even harder pressed to build more than a few nuclear warheads. North Korea has the most advanced nuclear program of the three, and the U.S. intelligence community estimates that it has enough nuclear material for two warheads at most. Any such warheads may not be small enough to place atop a missile. Of course, North Korea, Iran, or Iraq could use chemical and biological warheads instead, but doing so would, most probably, diminish significantly the lethality of any attack (while still risking nuclear retaliation). Consider the situation with a biological agent like anthrax. Not only is it difficult to deliver anthrax effectively by high-speed warhead, but if a missile were fired at the United States, Americans would know they had been attacked, possibly giving them valuable time to take cover and in any case providing an opportunity to seek prompt medical treatment against infection.

    The threat facing the United States also is not immediate. Although the U.S. intelligence community contends that North Korea, Iran, and Iraq "could" deploy long-range missiles, considerable disagreement exists over whether they will anytime soon. Moreover, recent political trends give reason to be optimistic that ballistic missile technology may not spread as rapidly as feared. North Korea agreed to freeze its missile flight-test program in 1999, in June 2000 the leaders of the two Koreas held a historic summit meeting in Pyongyang, and in October 2000 Secretary of State Madeleine Albright became the first senior U.S. official to visit the hermit kingdom. Iranian voters elected a more moderate Parliament in February 2000, and relations between Teheran and Washington may be slowly warming. Positive political trends do not extend to Iraq, however. Sanctions remain in place on Baghdad, slowing Saddam Hussein's pursuit of missiles and weapons of mass destruction, but international support for maintaining the embargo has frayed. If the sanctions regime ends, or if countries further ignore it, all signs indicate that Iraq will move rapidly to rebuild its arsenal.

    That some political trends are now working against missile proliferation and sanctions remain in place against Iraq weaken claims that the United States must launch a crash course to build missile defenses. Washington probably has time to do missile defense right and not just fast. Put differently, the risks of rushing outweigh the risks of being a bit more patient. By the same token, however, encouraging political trends are no reason to shelve the idea of missile defense or to adopt a casual and relaxed attitude toward missile-defense research. Political trends can reverse themselves overnight; North Korea may resume flight testing at a moment's notice, reformers may not gain control of Iran's military, and Iraq may succeed in acquiring a long-range missile capability. Indeed, continued vigorous U.S. missile defense efforts will keep the pressure on the international community to take nonproliferation more seriously; both China and Russia have pushed Pyongyang to moderate its behavior in a bid to show the world that the U.S. fear of North Korea is exaggerated. And in the long run, with the advent of a networked world and easy access to information, it may prove impossible to stem the proliferation of missile technology.

    Better Technology

    For decades, effective defenses against long-range ballistic missiles were derided as fantasy. Now many NMD critics agree that some kinds of defenses are becoming feasible. But considerable disagreement exists over which missile defense architectures make sense and how effective they are likely to be.

    The missile defense architecture that has attracted the most attention is the Clinton administration's proposal to build a midcourse interceptor system using "hit-to-kill" technology. Under this plan, the United States would eventually be able to launch interceptor missiles from bases in Alaska and North Dakota. Upon reaching space, these defensive rockets would launch "exo-atmospheric kill vehicles" that would try to destroy the attacker's warheads by ramming into them. In October 1999 the Pentagon demonstrated the basic feasibility of "hitting a bullet with a bullet" in a controlled test in which a kill vehicle destroyed a warhead 140 miles above the Pacific Ocean. Equipment malfunctions disrupted the next two tests, however, and the interceptors failed to hit their targets.

    These flight-test problems highlight the difficulties that plague the development of any major weapons system, especially one as complex as missile defense. Programs seldom proceed as smoothly, rapidly, or inexpensively as their strongest supporters contend. And while the Pentagon may eventually solve the engineering problems that have beset the NMD system that the Clinton administration proposed building, it remains questionable how well any midcourse interceptor can be made to work under operational conditions. Critics contend that because midcourse interceptors operate in the weightless vacuum of space, where there is no air resistance to help separate heavier warheads from lighter decoys, they are inherently vulnerable to simple countermeasures. Pentagon officials acknowledge that early versions of its midcourse interceptor would be vulnerable to "sophisticated countermeasures" but insist that its capabilities will be upgraded over time. It will be years before the tests needed to settle the issue can be conducted, but basic physics suggests that the Pentagon faces serious and innate disadvantages in trying to make a midcourse NMD system work against anything but a crude attack.

    The vulnerability of the Clinton administration's proposed system to countermeasures has prompted considerable interest in boost-phase technology. These defenses would shoot down missiles shortly after launch, before they reached space, and most important, before they could deploy warheads or decoys. In theory, boost-phase intercepts should be easier than midcourse intercepts. When a warhead reaches space, it is small, cold, and fast, making it difficult to locate and hit. By contrast, during boost phase an ICBM is moving relatively slowly and its rocket plume makes it easy to locate. The operative words, however, are "in theory." Serious work on boost-phase defense is only just beginning, and perhaps its leading proponent, physicist Richard Garwin, acknowledges that making it work will be "technologically challenging." No one knows yet how long it would take to build an operational system or how effective it would be under real world conditions.

    Even when the Pentagon solves these technological challenges, boost-phase defenses based on land or sea or in the air—the variants that have drawn the most political support thus far—are inherently limited: because missiles remain in their boost phases for only a few minutes, these defenses can work only if the defensive weapon is based within a few hundred miles of the launch site of the offensive missile. In many instances, therefore, boost-phase defenses would need to be based on foreign territory. This raises serious questions about such a defense's reliability in wartime. Moreover, earth-based boost-phase defenses cannot be used to protect the United States against Chinese or Russian missile attack—deliberate, accidental, unauthorized, or erroneous—because both countries are too large. That fact is seen as a virtue by some (including us), because it should ease the effort of gaining Russian or Chinese support for the system, but it is seen as a weakness by others. The geographical limitations inherent in earth-based boost-phase defenses lead many missile defense proponents to champion space-based boost-phase defense. But deploying boost-phase interceptors in space, and keeping them in good operational condition there, would be a monumental technological and logistical challenge that makes the idea a rather distant prospect.

(Continues...)

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Excerpted from Defending America by James M. Lindsay and Michael E. O'Hanlon. Copyright © 2001 by The Brookings Institution. Excerpted by permission. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

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