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Asymmetric Warfare
Like the young David with his sling-shot, hostile nations armed with cheap but effective weapons pose an increasing threat to the Goliath of U.S. military might.



Since the breakup of the Soviet Union in 1991, the United States has been the world’s sole superpower. It is the only country to maintain a global naval presence, a panoply of overseas bases, and the ability to deploy military forces to distant regions. The U.S. defense budget, at over $280 billion for fiscal year 2000, is several times larger than the combined spending of the countries generally perceived as the most likely future U.S. opponents: China, Cuba, Iran, Iraq, Libya, North Korea, Sudan, Syria, and Yugoslavia.1 No potential adversary comes close in advanced conventional weaponry—such as cruise missiles, stealth fighter-bombers, laser-guided bombs—and supporting navigation, surveillance, target-acquisition, and communications systems. Even the Pentagon predicts that a peer competitor will not emerge until around 2010, and most analysts consider that possibility unlikely.

Given U.S. supremacy in conventional forces, few rational opponents would deliberately seek a direct military confrontation with the United States—although Iraq blundered into war by miscalculating Washington’s response to the 1990 invasion of Kuwait and was soundly defeated. Instead, future adversaries who resort to military force against the United States will probably employ asymmetric, or David-and-Goliath, strategies involving innovative yet affordable weapons and tactics designed to weaken U.S. resolve and its ability to use its superior conventional military capabilities effectively.

A future opponent, for example, might employ nonconventional weapons—nuclear, chemical, biological, or radiological—or conduct terrorist attacks against military or civilian targets on American territory in a bid to deter or impede U.S. intervention in a regional conflict in the Persian Gulf, the Korean Peninsula, or the Balkans. Such an adversary could be selective in its objectives, timing the moment of an attack to maximize its strengths. Although the United States could ultimately prevail, the increased financial and human costs might undermine the political will of U.S. leaders to sustain the conflict or deter allies from providing assistance.2

U.S. Secretary of Defense William Cohen has warned that "a paradox of the new strategic environment is that American military superiority actually increases the threat of nuclear, biological, and chemical attack against us by creating incentives for adversaries to challenge us asymmetrically."3

To what extent is asymmetric warfare a new threat that poses a significant danger to the security of the United States? Three strategic assessments published by the U.S. Department of Defense have called attention to the issue.

The May 1997 Report of the Quadrennial Defense Review stated that a future adversary could "employ asymmetric methods to delay or deny U.S. access to critical facilities; disrupt our command, control, communications, and intelligence networks; or inflict higher than expected casualties in an attempt to weaken our national resolve."4

The National Defense Panel, a group of nongovernmental analysts commenting on the Quadrennial Defense Review, agreed that future opponents

will seek to disable the underlying structures that enable our military operations. Forward bases and forward-deployed forces will likely be challenged and coalition partners coerced. Critical nodes that enable communications, transportation, deployment, and other means of power projection will be vulnerable.5

Finally, Joint Vision 2010, a study of warfare in the next century by the Joint Chiefs of Staff, asserted that "our most vexing future adversary may be one who can use technology to make rapid improvements in its military capabilities that provide asymmetrical counters to U.S. military strengths, including information technologies."6

In response to these alarming declarations, skeptics have argued that military scenarios focusing on asymmetric threats tend to overstate the vulnerabilities of the United States, and that merely identifying theoretical windows of vulnerability does not necessarily mean that real-world adversaries could climb through them. These analysts allege that the Department of Defense has exaggerated the asymmetric threat in order to justify its inflated budget in the post-Cold War era.7

The following analysis concludes that while the threat of asymmetric warfare on U.S. territory is of real concern, a more likely scenario is that such tactics will be used to constrain the ability of U.S. forces to intervene in regional conflicts rapidly and at relatively low cost.

Numerous asymmetric strategies could be used to disrupt U.S. military capabilities and bring the conflict to the U.S. homeland. For example, high-tech and low-tech countermeasures could exploit the vulnerabilities of advanced U.S. weapons and their supporting systems. Information warfare could be used to disable computer networks, paralyzing communications, transportation, power systems, and industrial enterprises. Public-relations warfare might allow opponents to exploit the international news media to weaken the resolve of U.S. decision makers. Nonconventional attacks by special forces armed with chemical and biological agents could disrupt U.S. military operations. And foreign states could sponsor terrorist attacks against civilian targets to undermine public support for foreign intervention or to deter states from joining a U.S.-led coalition.


Given the Pentagon’s heavy reliance on high technology, future adversaries might develop relatively simple countermeasures designed to turn sophisticated U.S. military assets into wartime liabilities. Low-tech countermeasures, such as aluminum reflectors that confuse targeting radars and heat generators that deceive infrared sensors, are cheap and easy to use. During the 1991 Gulf War, Iraq employed several deliberate countermeasures and a few inadvertent ones. Although these tactics did not have a significant impact on the outcome of the war, they did reduce the effectiveness of some high-tech weapons in the U.S. arsenal.

For example, Iraq foiled intensive Coalition efforts to find and destroy its Scud missile launchers by deploying decoy missiles together with barrels of diesel fuel to simulate secondary explosions when hit.8 A crude Iraqi mine put out of action the Aegis missile cruiser U.S.S. Princeton, one of the U.S. Navy’s most advanced ships.9 Baghdad hampered sophisticated efforts to eavesdrop on its military communications by relying on buried coaxial and fiber-optic landlines that were hard to cut or tap, rather than using radio or satellite communications.10 And Iraq’s extended-range Scud ballistic missiles were so poorly constructed that they broke up under the stress of reentry, effectively creating a swarm of "decoys" around the warhead that confused the guidance system of the Patriot antimissile defense system. As a result, few if any Patriot interceptions were successful.11

A more sophisticated adversary might attempt to jam transmissions from the U.S. Global Positioning Satellite system, which aids many precision-guided weapons, or to sabotage critical command, control, and communications nodes such as satellite terminals and switching stations. Knocking out a few key nodes might disable a larger network of facilities supporting U.S. military operations. Nevertheless, such tactics are essentially defensive. While effective countermeasures might delay a U.S. victory and make it more costly, they would probably not change the outcome of a conflict, given the overwhelming superiority of U.S. military forces.

The Pentagon is concerned that adversaries or terrorists might employ software commands or malicious programs to shut down or disable key military computer systems. The fact that young hackers have been able to break into U.S. Navy and National Aeronautics and Space Administration (NASA) computers suggests that determined cyber-warriors from a hostile nation or a well-financed terrorist group might inflict considerably more damage. Programmable weapon systems may also be vulnerable to attacks by self-replicating computer viruses that erase stored data. According to Defense Secretary Cohen, "We have to spend a good deal more attention to looking at ways in which our reliance upon technology can be undone by a simple interruption."12

The cyber-terrorist threat also extends into the civilian sector. As the most computerized country in the world, the United States relies on a vast number of networked processors and databanks for the operation of its critical infrastructure—the system of interdependent industries and institutions that provide a continual flow of goods and services essential to the nation’s security and welfare.13 Such systems include energy distribution, transportation, banking and finance, water supply systems, emergency services, telecommunications, and continuity of government. This dependence makes the United States potentially vulnerable to deliberate cyber-terrorist attacks against critical government or corporate computer networks, with the intent to create massive disruption and chaos. According to the President’s Commission on Critical Infrastructure Protection, "We must learn to negotiate a new geography, where borders are irrelevant and distances meaningless, where an enemy may be able to harm the vital systems we depend on without confronting our military power."14

Some analysts have argued that cyber-attacks targeted at computerized systems for air-traffic control, the switching of commuter trains, or the control systems of a nuclear power plant or a chemical factory could kill large numbers of people. This threat appears to have been exaggerated because air-traffic, train, and power-plant and industrial control systems are not accessible through the Internet but have their own internal networks. For those networked computers that are potentially vulnerable to information attacks, defenses can be enhanced by investing in greater redundancy, encryption, electronic firewalls that insulate classified computers from the outside world, tagging of data to detect outside manipulation, and compartmentalization of computer systems so that they fail gracefully rather than catastrophically.15 The challenge is not the lack of available defenses but rather the will of government and industry to invest in them.

A potentially more effective form of information warfare in the military context is an enemy’s manipulation of the mass media to influence American public opinion, thereby restricting the U.S. government’s ability to employ its overwhelming military superiority. During the Vietnam War, the enemy’s use of asymmetric guerilla tactics and its ability to endure massive firepower while continuing to inflict American casualties gradually turned public opinion against the war and undermined the political will of policy-makers to sustain the conflict.

Since Vietnam, the U.S. public has become highly sensitive to casualties, particularly in military operations perceived as peripheral to the nation’s core security interests. During the U.S. intervention in Somalia in October 1993, irregulars associated with Somali warlord Mohamed Farah Aideed killed 18 American soldiers in the streets of Mogadishu, stripped a dead soldier’s body, and dragged it behind a truck in view of press cameras. These horrifying images aroused U.S. public opinion against the intervention and precipitated a rapid pullout. Given these precedents, a cunning adversary might take advantage of the "CNN factor" to weaken the resolve of U.S. policy-makers undertaking or merely contemplating a military intervention.

Iraqi President Saddam Hussein, for his part, has been able to exert substantial leverage against a vastly superior foe by exploiting the reluctance of the U.S. government to inflict civilian casualties, because of moral constraints and concerns about the negative political fallout in the Arab world. Fully aware of the American ability to strike at any target in Iraq, Saddam has situated key strategic assets such as biological-weapons plants in densely populated areas. Prior to the 1991 Persian Gulf War, he also arranged for the transportation of Iraqi citizens to potential bombing targets to serve as human shields. In this way, Saddam has repeatedly used his own civilian population as pawns in an asymmetric strategy designed to undermine the willingness of the United States to employ its overwhelming offensive capabilities.

According to one analysis, "Iraq…[has] taught the world how to put the most powerful military in history on a convincing America’s leadership that political defeat will be the price of military victory.... The lessons of America’s recent failure of nerve will not be lost on future opponents who lack its wealth, but possess the strength of will to fight with unconventional means."16

With the spread of chemical and biological weapons to states that sponsor terrorism — such as Iran, Iraq, Libya, Syria, and North Korea—the Pentagon is increasingly concerned about the potential for nonconventional attacks against U.S. forces.17 To be effective, such agents would not have to be delivered by missile or tactical fighter. Instead, they could be spread by low-tech delivery systems such as a modified agricultural sprayer mounted on a moving truck, boat, or aircraft.

During the Gulf War, U.S. military planners feared Iraq might employ its chemical and biological weapons against coalition forces deployed in Saudi Arabia, but fortunately these attacks did not materialize.18

Today, the massive battlefield use of chemical or biological agents is no longer considered the most likely threat, because it could provoke a massive retaliatory strike. A more plausible scenario would involve a series of coordinated, low-level attacks by special-operations forces or terrorists, delivered by covert means against multiple targets at home and abroad. Some chemical agents such as mustard gas and VX nerve gas, and biological agents such as anthrax spores, are highly persistent and could be used to contaminate airstrips and ports in order to disrupt military operations.

Since the end of the Cold War, the Pentagon has closed several bases overseas and at home and now relies far more heavily on a small number of facilities within the continental United States that might be vulnerable to sabotage.

A fictional scenario included in a 1997 Pentagon-sponsored study envisions an asymmetric attack by a future enemy with small amounts of chemical and biological agents to impede the U.S. ability to project power to a regional theater in a timely manner.19 In this scenario, Iraq again invades Kuwait, this time with the assistance of its erstwhile enemy Iran. Both countries recognize that if the invasion is to be successful, U.S. military intervention must be delayed, and covert chemical and biological attacks are seen as potentially effective for this purpose. Baghdad and Tehran decide to disrupt U.S. airlift and sealift operations by using a persistent chemical-warfare agent to contaminate key troop-deployment ports and airfields in the continental United States. They also release an incapacitating biological agent upwind of U.S. naval ships and other facilities on the island of Diego Garcia, the Indian Ocean base that was used in the 1991 Gulf War and in Operation Desert Fox. The attack is timed to trigger a major outbreak of incapacitating illness among American troops on the day of deployment.

This scenario is plausible in that airlift and sealift operations from U.S. bases at home and abroad are a potential Achilles’ heel. Particularly vulnerable are civilian support personnel such as stevedores and data-processing specialists working at ports and control centers, since few of them have been trained or equipped with protective gear against chemical or biological attacks. At the same time, some of the assumptions underlying the scenario appear unrealistic. How likely is it that Iraq would form a military alliance with Iran—its archrival for hegemony in the Persian Gulf and former adversary in a bloody, eight-year war—or that both countries would be capable of coordinating a complex series of political, military, and terrorist attacks?

The United States, the sole remaining superpower, has become a prominent terrorist target because of its global military presence, repeated interventions in distant conflicts, and prominent role in security alliances and peacekeeping operations. These activities have incurred the wrath of countries and groups that resent America’s power and perceived arrogance, its tendency toward unilateral action, its loyal support of Israel, and the corrosive effect of American popular culture on social and religious values. Thus, terrorist outrages against U.S. targets often represent a lashing-out against America’s predominant military, economic, political, and cultural influence.

Given the emergence of international terrorist operations on U.S. soil, such as the 1993 bombing of the World Trade Center in New York City, the Pentagon worries that state-sponsored terrorists might bring a future conflict to Main Street America by deliberately attacking civilian targets by asymmetric means. Rather than employing long-range ballistic missiles for strategic attacks on U.S. cities, hostile nations or state-sponsored terrorist organizations could smuggle nonconventional weapons into the United States in crates or suitcases. Multiple simultaneous attacks against domestic targets could constrain U.S. military operations abroad by creating a major political crisis at home. Alternatively, terrorist threats might be used for political blackmail, such as compelling the United States to withdraw its forces from Saudi Arabia.

Biological or radiological attacks on U.S. citizens could have delayed effects that might not be detected for days, giving the perpetrators time to escape and the state sponsor a chance of avoiding identification. Some have argued that if terrorists were to conduct an attack in a nonattributable manner, it would be politically costly for the United States to retaliate without compelling evidence of complicity.20

Nevertheless, the ability of U.S. intelligence and law-enforcement agencies to track down the perpetrators of unclaimed terrorist incidents should not be underestimated. Washington was able to link the 1986 bombing of a Berlin discotheque frequented by U.S. soldiers and the 1988 bombing of Pan Am 103 to Libyan agents, suggesting that it is not easy for a state sponsor to evade responsibility.

Even so, some terrorists may not be deterrable. A few terrorist groups may believe they can carry off a biological attack without attribution; others are transnational in nature and cannot be linked to one country, such as the Islamic fundamentalists involved in the World Trade Center bombing. Such groups are only loosely associated with a state sponsor or may carry out terrorist attacks on their own initiative. Moreover, some religious fanatics may be prepared to die for their cause.

In short, the primary aim of asymmetric warfare is to constrain the ability of the United States to intervene rapidly and at relatively low cost. It is important, however, to distinguish among the various asymmetric strategies, which range from low-tech to high-tech. Only relatively developed countries with extensive technical and financial resources have the potential to mount sophisticated attacks on U.S. weapon systems and computer networks. Yet few such countries currently have hostile or aggressive intentions toward the United States that would lead them down this path. Other adversaries, such as Iraq or Yugoslavia, may desire to bloody the United States’ nose, but they do not have the capability to carry out sophisticated attacks. By conflating these various actors and scenarios, the Department of Defense has tended to exaggerate the strategic significance of asymmetric warfare. It is therefore necessary to disaggregate these various threats if we are to assess them realistically.

Moreover, the Pentagon has so far made few real changes in force structure, weapon procurement, or military doctrine to address the purported vulnerabilities it has identified. To minimize the threat of asymmetric warfare to U.S. forces and weapons, the Department of Defense should consider some new policy options.

First, instead of devoting scarce resources to procuring Cold War-legacy weapon systems, the Pentagon should place greater reliance on long-range guided weapons that can hit targets from a safe distance, without the need for manned ships or aircraft to penetrate enemy defenses. The United States should also cut expenditures on a costly yet ineffective national antiballistic missile system and place greater emphasis on other types of homeland defense, such as enhanced protection of U.S. cities against terrorism with nonconventional weapons. "Star Wars" systems are impotent against the terrorist threat, which is far more likely to arrive by suitcase than by ballistic missile.

Second, if nuclear, chemical and biological weapons continue to proliferate, U.S. willingness to confront future aggressors may be sharply reduced. The Pentagon should retool its military strategy for a major ground war to minimize the number of lucrative targets vulnerable to nonconventional attack, such as dense concentrations of forces and centralized staging areas for logistics and reinforcements. U.S. troop units and weapon platforms should be reduced in size and increased in number to permit greater mobility and dispersal across the battle zone, thereby avoiding the creation of valuable targets. U.S. armed forces should also improve their capabilities to rapidly decontaminate large aircraft and ships, and—assuming that foreign nations will allow the establishment of new bases abroad—create multiple transshipment points to limit the vulnerability of airlift and sealift operations.

Third, the United States should enhance its ability to prevent and mitigate the consequences of chemical and biological attacks. On the prevention side, the intelligence community should upgrade its technical and human resources for monitoring enemy and terrorist acquisition of relatively small quantities of chemical or biological warfare agents. To mitigate the consequences of a possible attack, the armed services should develop and deploy improved sensors to detect and identify battlefield contamination, including low-level exposures to chemical nerve agents, which have cumulative toxic effects.21 The armed forces also need to provide protective training and equipment to key civilian defense workers. If the United States enhances and publicizes its ability to cope with the medical consequences of chemical or biological warfare, this capability would help deter such attacks.

Fourth, it is not clear that in the post-Cold War era, military intervention is always desirable or in the national interest. In the past, unilateral U.S. involvement in a regional conflict—particularly on behalf of one side in a civil war as in Vietnam, Nicaragua, and Somalia—has often proved counterproductive, eliciting widespread hostility on the part of those who resent perceived U.S. arrogance. Thus, one way to minimize the future threat of asymmetric warfare would be for the United States to employ greater restraint towards intervention in regional conflicts. Some analysts contend that by disengaging from secondary military commitments around the globe, the United States could reduce the incentive for terrorist attacks against Americans at home and abroad without adversely affecting its core security interests.22 Obviously, an activist U.S. foreign policy requires overseas bases and operations. As the world’s sole remaining superpower, the United States should be prepared to intervene when necessary to prevent genocide, to halt massive violations of human rights, or to contain regional aggression. Wherever possible, however, Washington should act as a member of a multinational coalition.

Finally, not all security threats are best addressed through military means. By strengthening nonproliferation treaties and export-control regimes designed to halt the spread of nuclear, chemical, and biological weapons, and by promoting diplomatic settlements of the festering conflicts in Yugoslavia, the Middle East, Southern Africa, and the Korean Peninsula, the United States can minimize the need for military intervention in the future. This diplomacy-centered strategy would require a much greater investment in nonmilitary instruments such as negotiation, foreign assistance, the promotion of democracy, and the effective use of the United Nations—including the full payment of back dues—backed up existentially with the big stick of U.S. military power.n

Jonathan B. Tucker is director of the CBW Nonproliferation Project at the Monterey Institute of International Studies, Monterey, CA.

1. Center for Defense Information, "The Fiscal Year 1999 Military Budget," Defense Monitor 27 (4) (1998), p. 2.

2. Christopher Gunther, "You Call This a Revolution?" Foreign Service Journal 75 (9) (September 1998), p. 22.

3. Center for Defense Information, "Military Domination or Constructive Leadership?" Defense Monitor 27 (3) (1998), p. 8.

4. US Department of Defense, Report of the Quadrennial Defense Review, "Section II: The Global Security Environment" (May 1997).

5. National Defense Panel, "Transforming Defense: National Security in the 21st Century," Joint Force Quarterly (Summer 1997), pp. 10-11.

6. US Department of Defense, Joint Chiefs of Staff, Joint Vision 2010 (Washington, DC: DOD, October 1997), pp. 10-11.

7. Carl Conetta and Charles Knight, "Inventing Threats," Bulletin of the Atomic Scientists (March/April 1998), pp. 32-38.

8. Rick Atkinson, Crusade: The Untold Story of the Persian Gulf War (Boston: Houghton Mifflin, 1993), p. 175.

9. Ibid., pp. 326-329.

10. Ibid., p. 439.

11. Theodore A. Postol, "Lessons of the Gulf War Experience with Patriot," International Security 16 (3) (Winter 1991/1992), pp. 119-171.

12. William Cohen, "Remarks on the Quadrennial Defense Review" (Washington, DC: Center for Strategic and International Studies; May 22, 1997).

13. Federal Bureau of Investigation, National Security Division, Counterterrorism Threat Assessment and Warning Unit, Terrorism in the United States 1996 <>, p. 19.

14. President’s Commission on Critical Infrastructure Protection, Critical Foundations: Protecting America’s Infrastructures, "Executive Summary" (October 1997), p. ix.

15. Richard Danzig, "The Next Superweapon: Panic," New York Times (November 15, 1998), p. A15.

16. Ralph Peters, "How Saddam Won This Round," Newsweek 132 (22) (November 30, 1998), p. 39.

17. Chemical warfare agents are supertoxic human-made chemicals such as mustard gas and sarin, while biological warfare agents include disease-causing germs, such as anthrax, and poisonous chemicals, such as botulinum toxin and ricin, made by living organisms.

18. "Hypothetical Biological Warfare Attack with Anthrax," in Albert J. Mauroni, Chemical-Biological Defense: U.S. Military Policies and Decisions in the Gulf War (Westport, CT: Praeger, 1998), pp. 216-217.

19. Booz-Allen & Hamilton, Assessment of the Impact of Chemical and Biological Weapons on Joint Operations in 2010 (McLean, VA, October 1997); see also "Germ War Games," Salon Magazine (February 9, 1998) <>.

20. Danzig, "The Next Superweapon: Panic."

21. US General Accounting Office, Chemical Weapons: DOD Does not Have a Strategy to Address Low-Level Exposures, Report No. GAO/NSIAD-98-228 (Washington, DC: GAO, September 1998).

22. See Christopher Layne, "The Unipolar Illusion: Why New Great Powers Will Rise," International Security 17 (4) (Spring 1993), pp. 5-51; and Eugene Gholz, Daryl G. Press, and Harvey M. Sapolsky, "Come Home, America: The Strategy of Restraint in the Face of Temptation," International Security 21 (4) (Spring 1997), pp. 5-48.

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