The bad news is that the United States today has no deployed capability to stop even a single intercontinental range (strategic) ballistic missile from reaching its territory. Similarly, nothing is in place that could intercept a shorter-range ballistic missile launched from a submarine or surface platform off the nation's coasts.
Seven years after Desert Storm, the United States has scarcely improved the protection it can afford forward deployed personnel and allies against theater ballistic missiles. Unfortunately, our potential adversaries have not stood still. If the United States today were to try to mobilize a new Gulf War-style coalition, how many takers would there be if London, Paris, or Rome—to say nothing of Riyadh—were at direct risk of missile-delivered weapons of mass destruction and the United States could offer no assurance of protection? For that matter, if Saddam Hussein had a missile capable of reaching the United States, would Congress, which narrowly approved going to war the last time, be willing to do so in the absence of effective missile defenses?
The Aegis Option
The good news is that the U.S. Navy is positioned to help the nation address this vulnerability—and to do so quickly, effectively, and relatively inexpensively. Thanks to its nearly $50 billion investment in the Aegis fleet air defense system, the United States already has deployed the infrastructure—platforms, launchers, missiles, sensors, command-and-control mechanisms, and personnel—needed to provide an early, worldwide defense against ballistic missile attack.
Such a capability could begin to be achieved quickly by making relatively small improvements in the existing Aegis system. In particular, the latest version of the Standard surface-to-air missile—the SM-2 Block IV—should be modified to optimize its missile-intercept capabilities. This would go beyond the development now under way of the SM-2 Block IVA, an endo-atmospheric or terminal phase missile interceptor (known as the Lower Tier or Area Defense System), to create a capability to perform such intercepts outside the atmosphere. This likely would involve adapting the Lightweight Exo-Atmospheric Projectile (LEAP) sensor/kill vehicle and deploying it on board the SM-2 Block IV, a configuration the Navy is calling the SM-3. This is the baseline approach for what has been known variously as the Navy Upper Tier and Theater Wide programs.
Because of the Aegis ships' ability to deploy forward and because of the rapid acceleration of its kill vehicle, the SM-3's defended area is substantially larger than that of the Patriot Advanced Capability Three (PAC 3) and Theater High-Altitude Area Defense (THAAD) systems. In the Middle East, for example, should a missile be launched from Libya or western Egypt at Israel, U.S. Navy ships operating in the eastern Mediterranean could obtain an intercept solution and execute one or more shots before the incoming missile was within range of Israel's Arrow antimissile defenses—and perhaps even before the Arrow radars could detect it.
Similarly, depending on the launch sites, U.S. vessels in the Mediterranean or Persian Gulf could intercept Iraqi or Iranian missiles launched at Israel, thereby reducing the number of warheads with which Israel would have to contend in the terminal phase. Navy ships off the Syrian coast may be able to assist in carrying out endo-atmospheric intercepts against short-range ballistic missiles in a manner that would be synergistic with Arrow's defensive operations.
Sea-based missile defenses are particularly well suited to such missions because of the inherent mobility and flexibility of their launch platforms. They can—and do—operate in international waters the world over, without requiring the permission of littoral states or even those we might wish to defend. This is particularly important in situations where the mere act of taking steps to improve an allied or host nation's defensive posture might be construed by some as provocative. For example, in the midst of the crisis over North Korea's nuclear capabilities a few years back, U.S. policymakers refrained from responding to the urgent appeals of the U.S. commander on the peninsula for the deployment of improved ground-based Patriot antimissile systems. Had the U.S. Navy's fleet in the region been equipped with its own missile defense capability, there need not have been such a lengthy—and potentially dangerous—deficiency in protection of U.S. forces and allies in the region.
Similarly, sea-based defenses, whether in the Persian Gulf or eastern Mediterranean, could ensure that needed protection is provided to America's friends in the Middle East, even under circumstances when policy considerations might preclude the timely deployment of U.S. equipment and personnel to the area.
If the Navy's systems are properly configured, those same ships also may be able to provide the first line of defense for the United States in the event that an attack involves long-range missiles headed toward targets at home.
The Navy Theater Wide system now being developed is fully supported by the Aegis SPY-1 radar. Its potential to contribute to national missile defenses, however, would be enhanced to the extent that it can obtain timely access to external data. Such data could come from other Aegis ships, aircraft, ground-based sensors, or space assets. Using the Cooperative Engagement Capability (CEC) now being introduced into the fleet, critical warning and tracking information can be transmitted in real time.
A Heritage Foundation-sponsored missile defense study team—whose members included former Director of Naval Warfare and Commander, Sixth Fleet, Vice Admiral J. D. Williams, USN (Ret.)—concluded that
providing targeting information to the Aegis system from these external sensors will supplement the information provided by the Aegis system's own SPY-1 radar and allow interceptors to "launch on remote data." This means the interceptor can be launched on the basis of information provided by external sensors and before the attacking missile is picked up by the SPY-1 radar. This would permit attacking missiles to be intercepted much earlier in their flight trajectories, substantially widening the area that can be defended, especially against higher velocity, longer-range theater ballistic missiles.
In principle, there is no reason why the SM-3 could not, in due course, be deployed on board platforms other than Aegis ships. With the connectivity made possible by CEC, such widespread deployment in vertical launchers fleet-wide would enhance greatly the global coverage of this missile defense system against longer- as well as shorter-range ballistic missiles.
That widely distributed system also would have the advantage of reducing the inherent vulnerability of a sea-based system to attacks using advanced antiship missiles such as the SS-N-22 Sunburn. Defeating this type of threat is, of course, a design requirement for the Aegis system upgrades independent of the ballistic missile defense mission. To the extent that other vessels—and perhaps allied combatant ships—are armed with the SM-3 and given access to the needed, real-time targeting data, a still greater capability could be achieved to provide protection for high value assets such as Aegis ships and aircraft carriers and large amounts of territory ashore. An obvious candidate would be Japan, which has built and operates its own Aegis ships under license and which recently has had the unpleasant experience of having its territory overflown by North Korea's Taepo Dong 1 ballistic missile.
The Baseline Approach
The large investment already made by the United States in the Aegis system permits an early, worldwide defensive capability to be introduced at a fraction of the cost of alternative approaches. The Heritage study estimates that the costs of such a deployment—to equip 22 Aegis cruisers with 650 modified SM-2 Block IV missiles—would be on the order of $2-$3 billion spent out over the next five years. This cost is hardly trivial, but it is far less than would be entailed in any comparable alternative.
Naturally, the ability of this sort of sea-based system to deal with attacks involving large numbers of ballistic missiles would depend not only on the quality of the individual ships' defensive systems but also on how many are within range. The beauty of the Aegis option is that—because of its relatively low cost and inherent flexibility—the amount of protection deployed in proximity to the threat could be adjusted, within reason, to meet perceived dangers.
In addition—because of the SM-3's large defended area—Navy ships can provide wide-area antimissile coverage without being tied to a specific operating area and without preventing ships whose vertical launchers contain these missiles from performing other assigned tasks. That said, if the threat grows significantly, the nation likely would want to acquire additional Navy assets to ensure that the needed missile defense capabilities could be provided in synergy with, not at the expense of, critical sea keeping, power projection, and forward presence missions.
Such additional procurements could be minimized, however, by increasing the performance of the first-generation sea-based missile defense system. One way to do this would be to field a larger and significantly faster interceptor missile than the SM-3. Such a missile would be equipped with a bigger, heavier, and more capable sensor/kill vehicle package than the LEAP and probably would require reconfiguration of some of the Navy's eight tube vertical launch systems into six-tube arrangements.
The performance of an Aegis-based missile defense system—and that of all antimissile systems—also would be considerably improved by the availability of targeting data from spaced-based sensors. Consequently, the United States should pursue the development and deployment of such sensors as a matter of the utmost urgency. If the threat continues to grow, more comprehensive global defenses should be deployed to complement the Navy's systems with effective space-based weapons.
The Obsolete ABM Treaty
There is only one impediment to providing competent worldwide missile defense from the sea: the United States is forbidden from doing so by the 1972 antiballistic missile (ABM) treaty. This accord, signed 26 years ago with the Soviet Union (a country that no longer exists) in a radically different strategic environment, prohibits effective strategic missile defenses, deployed at sea or elsewhere.
In deference to this treaty, which the Clinton administration insists is the "cornerstone of strategic stability," the Navy is unable to optimize the Aegis system to shoot down theater ballistic missiles. The administration is even more hostile to the idea of further evolutions of the Aegis option's missile systems or the external data it could use to improve the performance of a sea-based defense. Such measures would expand the size of the areas the Aegis system could defend and could enhance considerably the protection the Navy could afford to the American people. Such steps, therefore, clearly would be at odds with the ABM treaty's prohibition on territorial (or strategic) missile defense from the sea.
Worse yet, the Clinton administration has negotiated what amount to new treaties with Russia, Kazakhstan, Belarus, and Ukraine that have the effect of limiting even theater missile defenses (TMD). These arrangements would limit the speed and/or other performance characteristics of sea-, land-, or air-based TMD systems. (All space-based missile defenses would be banned.) Even though these controversial accords have yet to be submitted to the U.S. Senate for its advice and consent, the limits they impose are starting to insinuate themselves into the Navy's missile defense efforts.
The United States has continued to observe the treaty in the wake of the Soviet Union's demise, but it must not do so any longer. The compelling arguments for deploying a worldwide antimissile defense based on the Aegis program put into sharp relief the incompatibility of that accord with the nation's "supreme interests"—the grounds on which withdrawal from the treaty is permitted in accordance with its Article XV. It clearly is in the supreme interests of both the United States and its allies that the inhibitions on the deployment of effective antimissile defenses—which are an artifact of the Cold War and utterly incompatible with today's security realities—be dispensed with at once. The United States can accomplish this by announcing that it no longer will pursue unilateral adherence to the ABM treaty—to which it has remained bound as a matter of policy rather than international law. Alternatively, the nation could exercise its right to withdraw from that accord.
By making clear its willingness to use the six-month notice-and-wait period called for by the treaty's Article XV to seek a new modus vivendi with Russia—one based on mutual assured survival rather than on the United States' assured vulnerability—America can make clear that the deployment of its antimissile defenses will not constitute a threat to Moscow. Past experience suggests that once the Russians are persuaded that America is prepared to proceed unilaterally, they will stop trying to exercise a veto over needed U.S. self-defense capabilities.
The way ahead is clear. All that is lacking is the political will to implement it. It is in the vital security interests of the United States and its friends and forces around the world that it be found and translated into action.
Mr. Gaffney acted as Assistant Secretary of Defense for International Security Policy under President Ronald Reagan. He currently directs the Center for Security Policy in Washington, D.C.