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Assessing the Benefits of Defense

Making rational decisions on U.S. missile-defense policy requires weighing the potential security benefits and costs for both national and theater missile defenses. The benefits will depend on both the need for such systems and their likely effectiveness.

Proponents are seeking national missile defenses to protect U.S. territory against three possible threats: accidental or unauthorized launches of long-range Russian or Chinese missiles; deliberate attacks from China; and potential future attacks from other, hostile countries.

The possibility of an unauthorized or accidental launch of nuclear missiles is real. But missile defenses are not the best safeguard. In fact, deployment of national missile defenses could increase this threat, if it prompted Russia or China to rely more on launch-on-warning strategies or increase their alert rates. Other, cooperative measures would be more effective and less expensive. The nuclear powers could, for example, agree to install mechanisms to destroy errant missiles after launch, or to store warheads separately from missiles.

This approach has an added benefit: depending on where in the chain of command an accidental or unauthorized launch occurs, such an attack could be so large as to overwhelm a limited defense. Destroy-after-launch mechanisms would be able to address any size launch, and removal of warheads from missiles would preclude such a launch in the first place. If the United States is interested in resolving this concern, then working with Russia and China would be the best approach since it is clearly in their interests to prevent such launches, too.

The threat of a deliberate Chinese attack is very small, given the certainty of U.S. retaliation. Moreover, to retain its deterrent against the United States, China would take steps to prevent U.S. national defenses from being effective against its missiles.

The “rogue nation” threat has been exaggerated. Other than Russia and China, no country considered hostile to the United States has missiles capable of coming even close to U.S. territory.

There are five countries with missiles that are typically considered threats to U.S. interests: Iran, Iraq, Libya, North Korea, and Syria. Iraq, however, is not a realistic threat: its missile program is being dismantled under the terms of the UN resolution that ended the Gulf War, and long-term monitoring is being set up to ensure that Iraq will not be able to resume this program. All missiles deployed by the other four countries are either 300-kilometer-range Scud missiles acquired from the Soviet Union or derivatives of these missiles with ranges up to about 600 kilometers-well short of the 5,000-10,000 kilometers any of these countries would need to strike the United States.

Of the four remaining countries, North Korea has the greatest indigenous ability to develop longer-range missiles. However, despite reportedly working on a 1,000 kilometer-range missile-the “Nodong”-since the late 1980s, North Korea has yet to test a missile of this range. Foreign technical assistance could, of course, speed the development of longer-range systems in North Korea or elsewhere. But even with help, developing long-range missiles is a demanding and expensive process. And U.S. satellites would be able to observe missile flight tests, providing clear warning of threatening developments.

The other possible route for a developing country to obtain long-range missiles-acquiring them from one of the few countries that already has them-is highly unlikely. Long-range missiles are typically about 20 meters long and weigh many tens of tons, and are therefore essentially impossible to steal without the knowledge of the authorities. And it would be against Russia’s and China’s self interests to sell long-range missiles, because such sales would prompt severe economic sanctions under an international agreement prohibiting such transfers and because these missiles could be turned against them.

Moreover, even if a developing country did seek to attack the United States with weapons of mass destruction, long-range missiles are probably the least likely method it would choose. U.S. satellites would pinpoint the origin of any missile attack, so the threat of quick retaliation will be a powerful deterrent. Meanwhile, other methods of delivery, such as those used in the World Trade Center and Oklahoma City bombings and in the Tokyo subway gas attack, are relatively cheap, require only low technology, can be used clandestinely, and can be accurately targeted to make the most of a limited arsenal.

Leaving aside the question of the future threat, how effective might limited national missile defenses be if a threat did emerge?

The assumption that underlies current plans for national defenses-that incoming missiles would use no countermeasures- is unjustified. Any country that could develop a long-range missile could also deploy a variety of simple countermeasures that would make the job of the defense much more difficult if not impossible. Any missile delivering chemical or biological weapons can simply overwhelm the defense by using a large number of small warheads, called submunitions. A nuclear-armed missile can take advantage of the fact that interceptors for national missile defense systems are designed to work at high altitudes where, because of the thin atmosphere, objects of different shapes and mass travel at the same speed. This makes it possible to use lightweight decoys that simulate the warhead to create a large number of false targets or to hide the warhead in a large balloon so the interceptor would not know where to aim. Despite decades of work, the United States has not found a solution to the problem of such countermeasures.

Other ways to address the possible proliferation of long-range missiles are likely to be more effective and cheaper than missile defenses. Because U.S. satellites would provide warning of long-range missile development and deployment, the United States could destroy such missiles preemptively. More important, the United States has options available that could prevent a threat from materializing in the first place. Some diplomats believe, for example, that North Korea may be willing to bargain away its entire missile program in exchange for economic assistance, much as it did with its nuclear program.

The analysis for theater missile defenses is different. The short-range missiles possessed by Iran, Libya, North Korea, and Syria do represent a possible threat to U.S. troops or allies abroad. These missiles are armed with conventional warheads and possibly, in some cases, chemical or biological weapons. However, the 1,000-kilometer range Nodong missile reportedly under development by North Korea is essentially the longest range missile achievable using Scud technology; any theater missiles the United States will face in at least the medium-term future will have shorter reach. High-altitude defenses are not needed against this threat; low-altitude theater missile defenses are appropriate for this purpose.

Missile-defense proponents claim that short-range missiles will be relatively easy to defend against, but this may not be so. As with national defenses, the effectiveness of theater defenses will depend heavily on the countermeasures that the attacker uses. For example, the Patriot succeeded in all 17 of its intercept tests prior to the Gulf War, yet apparently shot down at most one, and probably zero, Iraqi missiles. The Scuds broke into several pieces as they reentered the atmosphere, inadvertently creating decoys and causing the warhead to tumble in unpredictable ways.

Incorporating countermeasures into any new theater missiles produced would be easier than building the missile itself, and retrofitting old missiles with simple and effective countermeasures would not be difficult. Both low- and high-altitude theater defenses would be defeated by submunitions. High-altitude defenses would also be susceptible to the same types of simple countermeasures as the national missile defense systems, thus shrinking the area covered by the defense. As a result, high-altitude defenses would provide little, if any, defensive capabilities beyond those provided by low-altitude defenses.

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