The terrorist attacks on New York and Washington on September 11, 2001, were both good and bad news for the Bush Administration's early commitment to the near-term deployment of defenses against ballistic missiles. The good news was that the vulnerability of the American homeland to devastating attack was demonstrated to be real, not merely a figment of the overactive imagination of Reagan-era strategists. The bad news, on the other hand, was that the method of attack utilized by the terrorists involved neither ballistic missiles nor nuclear weapons. Al-Qaeda's largely unanticipated concept--the use of fuel-laden commercial airliners in suicide missions to produce enhanced conventional explosive effects--inflicted less damage than might be anticipated from most so-called weapons of mass destruction, but it was well suited to a technically constrained and low-budget terrorist organization.

Critics of ballistic missile defense (BMD) were quick to seize on 9/11 as proof that the real threats of the future were likely to come not from intercontinental-range missiles with a recognizable "return address", but rather from a variety of possible weapons or devices clandestinely inserted into the United States, or even from aircraft or cruise missiles originating within the country or not far from its borders. They argued that states capable of attacking the United States with long-range ballistic missiles will continue to be deterred from such a step by America's overwhelming retaliatory capabilities. And missile defense is technically problematic and enormously expensive compared to other pressing defense needs.

But the debate over missile defense, nuclear strategy, and arms control ignited some twenty years ago by Ronald Reagan's Strategic Defense Initiative (SID) and sustained since then in well-worn paths is now winding down. The president's announced commitment at the end of last year to deployment of a limited BMD capability beginning in 2004 has made clear to all concerned that BMD in some form is shortly to become a reality. And yet bad habits contracted in the course of that debate continue to color much commentary on this subject. Perhaps the fundamental point is that missile defense must not be narrowly viewed in technical or purely military terms. The various technical problems and limitations of the BMD systems that the United States has had under development over the last two decades have figured prominently in the critics' case. While these challenges should not be underestimated, one would be foolish to bet against American technological ingenuity in the military realm, so spectacularly demonstrated in our recent demolition of Saddam Hussein's armed forces and regime; this is even more true now that the political constraints that hobbled BMD development in past years have been removed by American withdrawal from the Anti-Ballistic Missile (ABM) Treaty of 1972. Nor can the issue be reduced to a calculus of exchange ratios of the kind that so often dominated analyses of hypothetical nuclear conflict in the Cold War, though there are certainly abundant operational and tactical issues concerning BMD that remain to be addressed. Rather, missile defense needs to be analyzed as a strategic capability that is part of the larger tool kit of American power, one with an important psychological and political dimension that can generate benefits but also holds potential risks. Above all, missile defense must be considered not merely in relation to adversaries but as an instrument for reinvigorating existing alliances and forging new ones--indeed, as a central component of the "new world order" that is now being shaped by American global activism in the war on terror.

Getting Serious

In December 2001 the Bush Administration took a long-anticipated step away from the Cold War nuclear arms control regime by providing notice to Russia that the United States intended to withdraw from the venerable ABM Treaty. Critics of the Administration's commitment to BMD had predicted it would cause a diplomatic uproar, but Russian reactions were surprisingly muted, and previously vociferous European critics were as a result largely silenced. Indeed, the Russians began to talk increasingly of developing or enhancing their own defenses against rogue-state missiles, perhaps in cooperation with the Europeans or with the United States itself. Immediately following the treaty's expiration, the United States began aggressive testing of missile defense radars and interceptors in ways that would not have been permitted under the treaty regime. By the end of the year, enough progress had been made in various BMD technologies that the president felt confident in taking the next step, formal commitment to the deployment of a rudimentary BMD capability beginning in 2004.

In a statement released by the White House on December 17, 2002, the president emphasized the importance of missile defenses in the new strategic environment, where hostile states or terrorist groups not subject to the traditional calculus of deterrence can threaten the United States with catastrophic destruction. He also made clear that the commitment to develop viable BMD systems was not a narrow commitment to the integrity of the American homeland, but extended as well to American military forces deployed abroad and--not least--to the nation's friends and allies, and he declared obsolete the distinction between "national" and "theater" defense systems that the United States had previously observed in the context of the ABM treaty. He also called on other nations to join the United States in a common effort to develop advanced technologies for missile defense.

The detailed plan released by the Pentagon in conjunction with the president's statement distinguished initial capabilities from additional measures to be taken by the end of this decade. Initial capabilities were said to include up to twenty ground-based interceptors designed to destroy intercontinental ballistic missiles (ICBMs) in the mid-course phase of flight, with 16 of them to be based in Fort Greely, Alaska, and four at Vandenberg Air Force Base in California; up to twenty interceptor missiles based on U.S. Navy Aegis cruisers and destroyers with a capability to counter ballistic missiles in the boost or ascent phase; air-transportable pac-3 (advanced Patriot) systems geared to counter shorter-range ballistic missiles in the terminal phase of their flight; and upgrades to various sensors, including early warning radars located in the United Kingdom and Greenland. Additional measures to be pursued after 2005 were said to include additional ground- and sea-based interceptors; the Theater High Altitude Area Defense (THAAD) interceptor geared to shorter-range missiles; the Airborne Laser, a Boeing 747 equipped with a high-energy chemical laser capable of destroying missiles in their boost phase from hundreds of miles away (seven of these aircraft are slated for eventual procurement); enhanced radars and other sensor capabilities; and the development and testing of space-based defenses, including kinetic-energy interceptors. This program built on the BMD development effort of the Clinton years, but went beyond it in several ways, notably in its new emphasis on sea- and space-based systems, previously proscribed by the ABM Treaty.

Defense Department officials have emphasized that it is too early to predict the exact mix of capabilities to be deployed after 2005, but the intent is to create a multi-layered missile defense system capable of providing protection against the full range of potential "limited" ballistic missile attacks, whether on the homeland or on American forces or allies abroad. In this respect, the president's program differs dramatically from the original SID concept, which was directed to countering a massive Soviet nuclear attack. It is not designed to thwart an attack by contemporary Russia, with its much reduced but still very large strategic missile inventory. Nevertheless, robust BMD capabilities, actual or prospective, will necessarily have implications for America's strategic relationship with Russia and other current nuclear powers, as well as for international security more broadly. We will return to these important issues in a moment. First, though, it may be useful to restate the case for a limited American BMD system in our current security environment.

Why We Need It

Former Director of Central Intelligence George Tenet recently warned of the growing appetite of second-tier states for nuclear weapons and the weakening of international controls on them. Most dramatically, North Korea's break with the international non-proliferation regime in January 2003 and its preparations for resuming plutonium production in early March of that year seemed to make inevitable--barring unilateral military action by the United States, which seems highly unlikely at the present time--Pyongyang's emergence in the very near future as the classic "rogue state" possessed of nuclear-armed, long-range ballistic missiles with at least some capability to threaten the continental United States. Iran also appears determined to acquire weapons of mass destruction (WMD), in particular nuclear weapons, and the United States and its allies have become increasingly alarmed about the scale of the clandestine nuclear program it is pursuing in contravention of international safeguards.

In addition, only recently has it become clear to what extent the nuclear programs of North Korea, Iran and also Libya benefited from the technical assistance they received over many years from the putative renegade Pakistani scientist A. Q. Khan, the founder of Pakistan's own long-standing nuclear program. There is also some evidence that the Pakistanis may have worked out a secret agreement with Saudi Arabia to share nuclear weapons technology or missile systems.

There is also the danger that Pakistan's existing nuclear arsenal could fall into the hands of Islamic radicals should that country undergo a revolution or coup, a scenario that is far from outlandish given the internal turmoil created by the government's cooperation with the United States. The acquisition of such capabilities by a revolutionary Islamist regime would be most worrisome for the United States, especially given Al-Qaeda's efforts to obtain such weaponry on its own. And let us not forget the continuing danger of leakage of nuclear weapons, materials and expertise to rogue states and terrorists from Russia and other parts of the former Soviet Union.

Many continue to find comfort in the fact that no rogue states or entities currently possess ballistic missiles of true intercontinental range, even though North Korea is fast approaching such a capability. Yet shorter range missiles could be equally devastating if fired close to the United States. This is, after all, the lesson of the October 1962 Cuban Missile Crisis. Latin America and the Caribbean remain strategically important. The extensive presence in Panama today of a Chinese corporation with links to the People's Liberation Army has attracted little notice, but should at least raise some eyebrows in this context. Hizballah has for some time maintained a significant presence in the hemisphere. Finally, there is the scenario of shorter-range ballistic missiles launched against the United States from nondescript commercial vessels near its shores. We would be defenseless against such an attack.

Yet the greatest immediate threat to American interests posed by ballistic missiles is in fact not to our homeland, but to American forces and friends overseas. In recognition of this fact, as noted earlier, the Administration has formally ceased to draw a distinction between "national" and "theater" missile defense. Defenses against shorter-range, conventionally armed ballistic missiles are an increasingly integral aspect of American overseas power projection capabilities and therefore also of American alliance commitments. By the same token, effective protection of the American homeland against ballistic missile attack, far from encouraging a withdrawal to "Fortress America", can only strengthen the willingness of the American political leadership and general public to take risks on behalf of overseas allies and interests menaced by regional ballistic missile powers.

Two sorts of objections continue to be made to American BMD deployments from the standpoint of what might be called orthodox Cold War-era nuclear strategy. One is that such a step will only stimulate a new arms race either in numbers of offensive missiles or in technical countermeasures that would help them penetrate defenses. The other is that BMD is fundamentally unnecessary because even leaders of rogue states will continue to be deterred from attacking the United States by the threat of U.S. nuclear or conventional retaliation.

The answer to the first objection is that rogue states will have little ability or wherewithal to challenge American defenses, while major powers will not feel sufficiently threatened by the United States to invest large resources in what could well prove a futile competition in any case. It is by no means clear, as critics often assume, that cost considerations will continue to favor offensive over defensive systems--technological developments on the horizon, such as miniature autonomous mid-course interceptors, may well provide a significant cost advantage to the defense. More generally, the Bush Administration's oft-repeated argument that BMD will devalue ballistic missiles and discourage states from expanding their arsenals or acquiring them at all is in fact compelling.

To the second objection, several rejoinders are in order. First, it ignores the possibility of acquisition of ballistic missiles by terrorists lacking a return address and culturally and psychologically resistant to deterrence. Second, it may well overestimate the probability of success of pre-emptive attacks, as well as the likelihood of deterrence failure in the case of a rogue state leader who is actually under attack or has reason to believe an attack is imminent or fears for the demise of his regime. Finally, it ignores the possibility of accidental or unauthorized launch--something that should not be ruled out given the recent history of disastrous accidents in the Russian and Chinese submarine forces. BMD is the strategic equivalent of an insurance policy against unlikely catastrophes.

Costs and Tradeoffs

Persuasive as this case may be overall, there are still legitimate concerns, especially the costs and tradeoffs. As is the case with many experimental military programs, research and development (R&D) and projected operating costs for ballistic missile defense have tended over the years to outpace initial estimates, sometimes by very large amounts. Current spending for BMD R&D, at around $9 billion per year, is relatively modest by Pentagon standards, but acquiring and operating certain BMD systems will in some cases prove very expensive. Space-based systems raise particular questions, especially considering the technical risks, vulnerabilities, and political baggage associated with them. Just the new space-based infrared radar system for missile warning and tracking (STSS, formerly SBIRS-Low) will require a constellation of more than twenty satellites costing upward of $10 billion.

The costs of any defense systems can only be meaningfully analyzed by comparing the costs of systems performing similar missions or meeting other defense priorities. Ballistic missile defense necessarily competes with homeland security requirements that were scarcely on the national agenda before 9/11. Some of these requirements--defense of ports, for example--respond to threats that are at least as plausible as foreign ballistic missiles and could levy very substantial costs in force structure and operating expenses on the U.S. Navy and Coast Guard in the decades to come. BMD also competes with other forms of so-called active defense that meet plausible threats from cruise missiles, unmanned aerial vehicles, and small aircraft--increasingly potent threats even when armed with conventional explosives, due to the spread of precision-targeting technologies.

BMD has never been especially popular within the U.S. military because it has been seen as a competitor for scarce defense dollars, particularly at the expense of the strategic nuclear forces. Though theater BMD has gradually gained acceptance in military ranks as a critical enabler of American forward presence and attack operations, there is still substantial resistance to committing significant resources to national or homeland BMD.

This brings us to the second area of concern. From the 1980s onward, national missile defense in the United States has been driven by an unhealthy combination of technological and political factors. Without denying the necessity of political leadership here, it has to be recognized that the ideological controversies over BMD and the absence of a stable and vested BMD constituency in the military and in industry have resulted in a history of erratic and politically inspired decision-making. At the same time, and paradoxically, they also led to a certain abdication of strategic direction in favor of bottom-up technological experimentation, in an effort to fly under the radar of intellectual and political controversy and to kick key decisions as far as possible down the road. To his great credit, George W. Bush has been willing to take crucial political decisions concerning the future of BMD. It is hard to quarrel with his decision to begin fielding some capability as soon as possible in spite of technical and programmatic risks, given the sorry history of procrastination in this matter, especially during the Clinton years, as well as the gathering threat. At the same time, it is also difficult not to wonder whether technology remains too much in the driver's seat. There is as yet no clearly articulated strategic framework that would provide a basis for doing the appropriate cost-tradeoff analyses and--what is perhaps most important--for reassuring allies and adversaries alike about American intentions in this sensitive and contentious area of international security. Other nations are unlikely to make substantial financial or political commitments to joint technology development with the United States absent a reasonable strategic roadmap.

International Complications

While America's present global dominance will almost certainly rule out classic, Cold-War style arms races, there can be little doubt that Russia and China, as well as other possible adversaries, will explore avenues that offer asymmetric advantages relative to the American defense posture generally. Elements of the Russian military and political elite, for example, view any substantial American BMD effort with foreboding, and are actively seeking to develop ways to counter or neutralize it in order to preserve the viability of their ballistic missiles, which remain the sole effective instrument of Russian global power projection.

Yet, the Russians have already recognized that they have a substantial interest in common with us in discouraging and defeating missile attacks originating in the Middle East--to which they are of course much more directly exposed at present than is the United States. There are interesting possibilities for collaboration with Russia in theater missile defense, and perhaps especially in boost phase systems situated on Russian territory. But we also have to recognize the continuing sensitivity of the Russians to the prospect of a global missile defense capability monopolized by the United States--something that would in their eyes give the United States an unparalleled ability to threaten the security of the Russian state. Accordingly, in the near term we need to explore the possibility of forming a special security relationship with Russia centering on some sort of limited missile defense cooperation, while at the same time demonstrating prudent restraint in the reach of the BMD architecture we decide to develop. This might involve a more or less formal understanding relative to space-based BMD or space-based weaponry in general (on which more in a moment). Over the longer term, when a new generation has taken the reins in that country, the time may arrive when Russian attitudes in these matters are more relaxed.

As for China, the Administration has for various reasons been reluctant to spell out the anticipated impact of the American BMD program on the Chinese strategic missile arsenal. China has been given assurances from time to time by American officials that the program is not directed at that country. It is hardly surprising that the Chinese have had difficulty taking these assurances seriously. Bluntly stated, there is no escaping the fact that a limited American BMD program that is worth anything will be inherently capable of seriously degrading if not simply stopping any attack on the American homeland by Chinese strategic forces now and for some years to come. China currently has some twenty operational ICBMs presumed to be targeted against the continental United States, and a handful of sea-launched ballistic missiles (SLMBs) in a single aging and unreliable nuclear-powered submarine. Even if the Chinese upgrade their strategic missile force with multiple warheads and penetration devices of various kinds, as they are reportedly in the process of doing, or expand it incrementally, it is far from clear that they could stay ahead of American countermeasures or additional defensive deployments even if they chose to do so.

Is there any reason to continue to grant Chinese nuclear missiles a free ride to the United States? One of the standard complaints among critics of BMD is that it threatens the "stability" achieved during the Cold War by fostering a new arms race between offensive and defensive systems. For example, some have predicted that China would respond to an American missile defense system by a major buildup of its ICBM force, which in turn would lead India to expand its own missile force and thus trigger a new arms race between India and Pakistan to the general detriment of the strategic balance in Asia.

There is little evidence to support such hypotheses. The Chinese have preferred to invest their missile dollars in shorter-range conventional systems designed primarily to exert pressure on Taiwan (and to a lesser extent Japan), and in new mobile ICBMs and SLBMs that will provide them for the first time with a secure second-strike capability as a hedge against pre-emptive attack by the United States. The Chinese are no doubt keenly aware that recent technological advances by the United States hold great promise for improving the relative efficacy of defensive systems. They are very unlikely to invest in large numbers of modern long-range missiles that could be rendered totally ineffective within a few years by (relatively inexpensive) defensive innovations.

China is much more apt to concentrate its limited resources on building a capability to deny the United States easy access for its naval and expeditionary forces to East Asia and its allies there. But how vigorously they pursue such advantages will depend to a considerable extent on their perceptions of American intentions. This is why the United States cannot afford to pursue its missile defense project in isolation from its overall foreign policy. While the United States should make clear to China that it reserves the right to defend its national territory from all potential threats insofar as it is able, we should continue to avoid defining our military requirement for a BMD system with specific reference to an actual or potential Chinese threat to the American homeland; and the extent of U.S. support for regional missile defense in the western Pacific should be conditioned on the evolution of Chinese strategic behavior in the region as well as its democratic development.

Involving Allies

The United States needs to make clear to its traditional friends and allies the role it envisions for them in a new international security system centrally featuring defense against missile-delivered WMD. Many have wondered whether NATO still makes sense in a world in which there is no longer a plausible conventionally armed adversary close to its borders. Missile defense provides an attractive common mission for the alliance as a whole, one that is likely to be decreasingly controversial as potential threats loom larger on the horizon and the Europeans get over their nostalgia for the comfortable assumptions of the Cold War security environment. The United States must take the lead not only in technical-industrial cooperation in BMD development, but in shaping political expectations on the part of our NATO allies concerning the overall architecture of a NATO BMD system, burden-sharing arrangements, the problem of constraints on technology transfer, rules of engagement, operational command and control, and a host of related issues that have as yet barely been articulated publicly. The good news is that there appears to be a growing consensus throughout Europe that missile defense makes sense and is something that needs to be carefully studied. And just recently, the Europeans invested some $3.5 billion in an anti-tactical ballistic missile defense capability for the existing Aster air defense system, to be based at sea as well as on land. These are important developments.

In Asia, a major breakthrough occurred in August 2003 when Japan announced its intention to spend $1 billion per year through at least 2007 to develop, in close collaboration with the United States, a nationwide BMD system utilizing its existing U.S.-made Aegis destroyers as well as the pac-3 system. Assuming relevant political and constitutional issues can be resolved, this development could help raise the U.S.-Japanese defense relationship to a new plane of truly global rather than just regional cooperation. In addition, Australia has made a public commitment to develop its own sea-based BMD capability in collaboration with the United States.

Mention should also be made of the special relationship the United States maintains with Israel in the BMD area. The two countries have jointly developed the Arrow anti-missile system, which is now operationally deployed in Israel and is expected to play a critical role in deterring or defeating missile attack by Israel's various regional adversaries. It may be worth contemplating a more formal relationship with the Israelis on these matters, perhaps in cooperation with other friendly regional states or even as part of an American guarantee of a final Israeli-Palestinian settlement.

A final word about space. Bush's willingness to pursue missile defense technologies that could be based in space does not yet amount to a policy of militarizing space, but it certainly raises a question as to the ultimate intention of the United States in this area. It may well accelerate efforts by other nations (particularly the Chinese) to develop space weaponry or otherwise to erode existing constraints on the use of space for military purposes. It is not at all clear that this would be in the best long-term interests of the United States. The United States is militarily more dependent on space now than any other country. Adversaries may well see attack on American space systems as the core of an asymmetric strategy to counter our conventional military power.

Having said all this, it may well be the case, as is now commonly said within the American defense community, that the militarization--more precisely, the weaponization--of space is inevitable, and that the United States has to be prepared not only to hold its own in space but to dominate space as it now dominates the oceans. It would be rash, however, to precipitate such a development by a narrow calculus relating to the advantages of space-based missile defenses. The United States needs a coherent strategy--integrating political, military, civil and commercial considerations--to govern its policy and activities in space in the new century. The recent space shuttle disaster is but one indication of the distance that has to be traveled in this regard. One possible approach might be for the United States to refrain from basing weapons in space so long as other nations did the same, but to maintain a capability to do so in a relatively short period in response to certain contingencies, such as proliferation of anti-satellite weapons, a quantum increase in the Chinese ICBM/SLBM force, or a sharp deterioration in U.S.-Russian relations.

The United States needs missile defense now more than ever. The U.S.-Soviet relationship during the Cold War may well have been less stable in retrospect than was generally thought at the time, but the prospects for the use of mass destruction weaponry are certainly greater today than at any time since at least the Cuban Missile Crisis. With North Korea's departure from the international nonproliferation regime, we may well face a set of cascading effects that will push more countries to pursue more seriously ballistic missile and WMD options. (Already, the Japanese are beginning to talk openly about the need to reconsider the nuclear option in reaction to North Korean developments.) Critics continue to complain about the costs of missile defense and to question its technical feasibility. It is increasingly clear that such concerns are misplaced. The costs of the current development effort are modest. Building and fielding every system we are now working on would clearly be prohibitively expensive, but is not likely to happen. We can be fairly confident that a reasonable relationship will be maintained between the evolving BMD architecture, the nature of the emerging threat, and other military and national needs. As for feasibility, to repeat what was said earlier, it would be rash to wager that the United States will fail the technical challenges we face. The more daunting challenge will be to think through the manifold ways our new commitment to missile defense--both national and global--will contribute to the political fortunes of the United States in its current unipolar moment.