The Anti-Access Threat and Theater Air Bases


The Department of Defense (DoD) in its 2001 Quadrennial Defense Review (QDR) concluded that the “anti-access” threat—the complex mix of political, geographic, and military factors that could prevent or delay US forces from deploying to a combat theater—is the dominant strategic challenge confronting future US power-projection operations in regions of potential conflict, particularly in Asia.

To analyze the seriousness of this challenge, this paper focuses on one key aspect—the potential vulnerability of theater bases for land-based fighter aircraft. American combat air power, provided primarily by the United States Air Force (USAF), plays a critical and growing role in US power-projection operations. Over the next two to three decades, Defense Department combat aircraft plans are focused on modernizing the fighter force. Should emerging anti-access threats undermine theater fighter base viability, future US military operations could be jeopardized.

To conduct this analysis, this report addresses four key related issues:

  • What are the basing and logistical requirements for land-based fighters in future combat operations?
  • To what extent do these kinds of bases (and supporting logistics) exist?
  • How vulnerable are these bases to political access problems and to emerging military threats?
  • What potential counters are available to minimize these threats?

This report suggests that over the long run, the combined uncertainties raised by political factors, logistics, and emerging military threats mean that the combat power of the land-based fighter force may be significantly constrained in supporting US power-projection operations in an anti-access environment. To hedge, the Defense Department should adjust its current combat aircraft modernization plans, which focus primarily on the acquisition of fighter aircraft, to increase spending on
systems less reliant upon forward bases.

The issues raised in this analysis have broader strategic implications for the US military as a whole.

Reliance on large, fixed facilities in the theater of operations is much more than an Air Force issue.

Given the growing role of air power forces in US military operations, constrained USAF fighter operations would increase the vulnerability of joint forces to military threats and decrease overall force effectiveness. Army, Navy, and Marine forces are dependent upon forward ports, airfields, and bases in the theater to conduct combat operations. Many of these forces must engage adversaries at much shorter distances than land-based fighters, thus exposing them to even greater risk from anti-access threats. The susceptibility of these force elements to emerging anti-access threats may differ from land-based fighters due to force characteristics, logistical requirements, and basing modes, but should be analyzed in similar detail to guide decision-making on future force posture and force modernization priorities.

SUMMARY RESULTSWhat Are the Basing and Logistical Requirements for Land-BasedFighters in Future Combat Operations?

Taking into account the inter-related factors of aircraft characteristics, aircrew fatigue, combat mission profiles, aerial refueling requirements, sortie rates, and aircrew to aircraft ratios, landbased fighters typically will require bases within 1,000 to 1,500 nautical miles of enemy borders to conduct effective operations.

Based on historical requirements, five theater bases would be required for each Aerospace Expeditionary Force (AEF), which contains approximately two traditional wings of fighters. The Vietnam conflict required almost six AEF equivalents; the Gulf War around five; Serbian operations about two.

Forward-based fighters must be supplied with munitions and fuel to conduct sustained operations.

Depending on aircraft type, each deployed aircraft would consume three to eight tons of current generation weapons per day (though these requirements will decrease with future weapons) and about double that tonnage in fuel. Depending on the base, the United States may need to deploy additional equipment to support operations.

To What Extent Do These Kinds of Bases (and Supporting Logistics) Exist?

Overall numbers of developed airfields increased dramatically around the world following World War II under the impetus of two main drivers: Cold War imperatives and commercial air traffic growth. Base infrastructure development was most concentrated in Europe, Northeast Asia, and the Persian Gulf. In most of Asia, the emerging focus of current Pentagon planning, the basing infrastructure is less developed. Analysis of the global airfield data base1 illustrates that Asia contains
only about 14 percent of the world’s airfields. Half of these are located in the developed nations of Australia, Japan, and South Korea. As the Defense Department recently concluded regarding Asia “the distances are vast….The density of US basing and en route infrastructure is lower than in other critical regions. The United States also has less assurance of access to facilities in the region.”

Experience from numerous conflicts, notably the 1967 and 1973 wars between Israel and Arab  states, has demonstrated the critical role hardened aircraft shelters play in reducing vulnerability to air base attacks. Fifty-two bases in Asia—about 18 percent of the total—field a total of 1,412 hardened aircraft shelters. At first glance, this large number would appear sufficient to house US
deploying fighters, but availability is likely to be lower for several reasons.

Reflecting 50 years of preparation for war, almost half (641) of the total shelters in Asia are concentrated in South Korea. Employing these bases to conduct operations other than for South Korea’s defense raises uncertainties; South Korea may be reluctant to get engaged, while the bases could come under heavy attack
from North Korea should a conflict widen. Most of the other shelters are located in Japan (107) Taiwan (203 shelters), India (229 shelters) and Pakistan (176 shelters)—an average of about 180 per nation, sufficient to shelter a single AEF. But the total number available for use could be reduced by several factors. Are these widely separated bases located in the right position for the conflict? Will the nation support combat operations from its soil by US aircraft? Finally, each nation fields substantially more combat aircraft than shelters. Accordingly, the host nation would need to expose more of its own aircraft to attack in order to shelter US aircraft. All this suggests that the number of shelters available for use will be lower than the total and in a larger-scale conflict, significant numbers of US fighters could have to deploy to unhardened bases.

Regarding logistics, forward-deployed aircraft require fuel and munitions to operate from host nation airfields. Aviation fuel could be readily available; if not, fuel is a fairly fungible commodity that, with sufficient time, could be provided to the fighting force. Fuel production, storage, and distribution facilities would, however, remain vulnerable to attack. Supplying munitions has historically been the most  challenging logistical task, but advances in munitions technology offer the potential to increase radically US flexibility in supporting deployed forces.

How Vulnerable Are These Bases to Political Access Problems and To Emerging Military Threats?

Political Anti-Access Threats to Forward Bases

Although the number of airfields has increased around the world, the USAF’s overseas basing posture has declined because of changing strategic circumstances, budgetary pressures, and internal opposition from host nations. To employ forward bases and air space, the United States will need political support from host countries. Political access problems have erupted in almost every
contingency and conflict in which the United States has engaged since World War II. The United States has powerful economic, diplomatic, and military cards to play in securing access—and has employed these cards successfully in many crises. But historical evidence also demonstrates that on many occasions, difficulties in obtaining political access to airspace and bases has constrained US power-projection capabilities.

The attitude of host countries regarding access in future crises is difficult to predict, raising significant uncertainties regarding the basing and employment of combat aircraft. The United States can bring enormous pressure to bear on a host country to accept US forces, but success, as has been seen in numerous crises, cannot be guaranteed.

Military Threats to Theater BasesDeep-Strike Systems

Many potential adversaries are increasing their emphasis on the procurement of ballistic and cruise missiles. Government intelligence forecasts anticipate adversaries possessing larger numbers of longer-range ballistic and cruise missiles. The proliferation of satellite navigation systems, sub-munition warheads, and re-entry vehicle guidance systems has the potential to increase dramatically
ballistic missile accuracy and lethality. Long-range, land-attack cruise missiles, which offer even higher accuracy than ballistic missiles, continue to proliferate. In addition, the new generations of ballistic and cruise missiles entering service can be fired from mobile launchers, which are much more difficult to locate and attack than fixed launch sites.

Multiple nations are placing commercial reconnaissance satellites into orbit that could provide adversaries with precision information to target their growing deep-strike arsenals. Commercially-based imagery can pinpoint the forward deployment and disposition of American and allied military forces in the region to facilitate the timing and effectiveness of enemy strikes. Attempts to control access to satellite imagery will prove increasingly difficult as the number of imagery
sources grows. Hardened military air bases are resilient entities. Historical evidence illustrates that large numbers of precision weapons would be needed to knock a hardened military air base out of commission for a substantial time period. The same does not hold true for less protected military and commercial airfields.

At unhardened airfields, aircraft parked on ramps, fuel stocks, and munitions would be vulnerable to the new threats. Capabilities to restore runways, electrical power, and fuel supplies would be less resilient than at hardened military airfields.

Toward the end of the Cold War, the USAF found it could not afford to ensure the survivability of its air bases in Europe. The sheer mass of anticipated Soviet attacks had the potential to overwhelm available passive and active defenses. The future ballistic and cruise missile threat has different characteristics: less mass but much greater precision. These weapons are less threatening to hardened facilities and runways than traditional strike aircraft, but potentially more devastating against
aircraft parked in the open, fuel facilities, and munitions storage areas.

Special Forces Attacks

Since 1942, special forces worldwide have conducted 645 separate attacks on airfields to destroy over 2,000 aircraft on the ground. Special forces pose a growing potential threat because of the proliferation of more accurate stand-off weapons, which increases the perimeter US forces must defend. The most worrisome threats include precision munitions for mortars (which would enable attackers to hit high value targets with a small number of rounds); long-range, large caliber sniper rifles (which could be used against high-value aircraft to knock out key components);  and anti-tank rockets (which could be used to penetrate aircraft and personnel shelters).

Weapons of Mass Destruction

Weapons of mass destruction (WMD) employed against an air base have the potential to disrupt the flow of US forces into a region, degrade combat sortie generation rates, and kill large numbers of US personnel. A nuclear strike could obviously knock a base out of action. US forces are trained to operate in a chemical or biological environment, but the presence of such substances could slow the pace of operations.

US policy is to deter WMD use with the threat of retaliation. This policy apparently succeeded in the 1991 war with Iraq. The United States would also, as was seen in the Gulf War, attempt to destroy an adversary’s weapons, research facilities, and means of delivery to reduce the threat to US and allied forces. The Gulf War highlighted the multi-faceted difficulties confronting such operations.

The presence of WMD raises two key access-related issues:

  • Allies may be deterred from granting access to US forces in order to prevent WMD employment on their soil.
  • An adversary possessing WMD is bound to make a US decision-maker reflect carefully about placing aircraft and thousands of US personnel in harm’s way on forward air bases.
Are There Potential Counters to Anti-Access Threats?Political initiatives

The United States should engage as wide an array of nations as possible to increase the chances of obtaining access when needed. Nonetheless, history illustrates that the unpredictability of the location and nature of future conflicts will make it difficult to forecast the attitude of host country when access is needed.

Infrastructure Development (Base Development, Pre-Positioning)

To augment the current basing infrastructure in Asia, developing additional hardened facilities would be an option; however, one that will take time. Developing a similar network of facilities in Western Europe and the Persian Gulf took decades of sustained effort. Unfortunately, Asia’s vast size combined with the range limitations of fighter aircraft demands enormous prescience in predicting accurately the general location of future conflicts. Given such vast distances, the United States could expend enormous resources on base infrastructure development and “get it wrong.”

The high cost is also a significant complicating factor. Trying to hedge bets by conducting base development in multiple locations would cost tens of billions of dollars. The cost of base development just in Saudi Arabia—a single country with a much smaller land mass compared to Asia— was estimated at over $30 billion in current year dollars. Even with this significant investment, most US aircraft were forced to park in the open during the 1991 Gulf War. Developing hardened bases in Europe was even more costly and, by the end of the Cold War, still insufficient to protect many deployed USAF aircraft.


Dispersing the force across more airfields would be an obvious counter to reduce vulnerability at unprotected airfields. To implement such dispersal concepts, the USAF would need to invest more heavily in its support structure. Dispersal proposals developed during the Cold War were constrained because of the  significant costs of expanding the support structure (more ground support equipment, maintenance personnel, and base security) and reconfiguring all aircraft (to improve their capability to operate from austere fields). Dispersing the force would also require access to more airfields at a time when the US is concerned about gaining access to sufficient bases using traditional concentrations of aircraft.

Suppress Anti-Access Threats Rapidly

The USAF currently plans to employ the B-2 and F-22 force, working in conjunction with carrier air power and naval surface combatants and submarines, to neutralize enemy mobile air defense system; strike enemy airfields (to eliminate enemy aircraft); shoot down enemy aircraft; hunt down mobile enemy ballistic and cruise missiles; knock out WMD production and storage facilities; and, if necessary, deal with enemy ground offensives. Because of the small size of the USAF “access insensitive” force and the size of the job, such operations could take a  considerable amount of time, particularly if an adversary conceals its missile forces until US forces begin deploying (and thus constitute a more lucrative target).

Large Manmade Islands

In the 1990s, the Office of Naval Research sponsored a science and technology program on what was termed the Joint Mobile Offshore Base (JMOB)—a large floating structure capable of handling land-based aircraft and providing logistical support. Such bases would greatly increase US flexibility in deploying aircraft forward, but may also present an opponent with an attractive target.

The cost of a single JMOB was estimated at about $6 billion, but the concept currently has no ardent supporters in the Pentagon.

Active Defenses

Active defenses could help alleviate concerns if they become effective, but uncertainty remains whether US missile defense systems, once fielded and deployed, can reliably defeat enemy ballistic missiles. Indeed, a primary reason these weapons are proliferating is the difficulty of defending against them. Cruise missiles also pose challenges. If successfully detected, cruise missiles can be
engaged successfully by a variety of platforms, but maintaining defenses constantly on alert would strain the deployed force and reduce US offensive capabilities. Overall, an adversary could probably overcome US defenses by fielding sufficient numbers of missiles to conduct massed volleys; some missiles would probably get through to inflict damage on forward bases.

Base Outside the Range of Threat Systems

If adversaries can threaten US bases within 1,500 nautical miles, fighter operations over extended ranges become less viable and call into question current US aircraft modernization policies. Long-range systems would increase US basing options and decrease the number of enemy systems that can attack US bases. But a new long-range system will take time to develop. Air Force estimates do not envision a new long-range system entering service for another 20–30 years, while the  economic and political challenges involved in developing and fielding a new system are substantial. For the near to medium term, Air Force options include expanded purchases of stand-off weapons, additional B-2 procurement, adding refueling capabilities to the proposed Unmanned Combat Air Vehicle (which would not have the pilot fatigue issues that constrain the mission radii of fighter aircraft). The Defense Department could also consider increasing reliance on maritime forces  such as aircraft carriers, surface combatants, and submarines.


The requirement to base fighters within 1,000 to 1,500 nautical miles of an adversary raises three key issues:

  • Can the United States count on getting access to forward bases? Trends here appear negative. The US peacetime, foreign basing posture has declined precipitously since the Cold War. US long-term presence has stimulated indigenous opposition, and access constraints continue to bedevil combat operations. Predicting the attitude of host nations regarding access in a future crisis remains difficult.
  • Will adversaries deploy sufficient numbers of long-range ballistic and cruise missiles to threaten forward bases? Longer-range weapons are more expensive than shorter-range variants, which raises an adversary’s cost of fielding large numbers. But ignoring this threat does not seem acceptable. Over the long-term, the United States would be placing a significant portion of its combat capability at risk. Analysis of potential counters to make forward bases less vulnerable—hardening, dispersal, and missile defense—indicates that these may be imperfect and possibly unaffordable solutions. The USAF reached a similar conclusion at the end of the Cold War regarding air base survivability in Europe. Perhaps the USAF’s Global Strike Task Force in combination with maritime forces will prove successful in neutralizing an adversary’s deep strike systems, but the small size of the USAF’s access insensitive force combined with the magnitude of the operational tasks it must achieve causes concern. It also raises some difficult problems regarding logic for the USAF. If these small forces can succeed in this most difficult and challenging set of tasks, what is the justification for the rest of the force? Why not simply increase the size of the access insensitive force to increase the chances of success and use these for the duration of the campaign?
  • What will be the effect of adversaries possessing WMD? The threat of WMD strikes would appear to reduce both allied willingness to host US forces and US decision-makers’ willingness to risk deploying forces.

To project power, US forces relying on forward bases require success in four areas: an adequate base infrastructure, responsive logistical support, political approval from host nations, and effective counters to enemy threats. If one of these factors is missing, US power-projection capabilities will be compromised. The problem facing the United States is that even a high probability of success in each factor results in an overall low probability of success. For example, with a 90 percent chance of succeeding in each area, only a 65 percent overall probability of success results (90 percent X 90 percent X 90 percent X 90 percent = 65 percent).  In short, these combined uncertainties suggest that over the long term, the land-based  fighter force could be significantly constrained in supporting US power projection operations.

In the 2001 QDR, the Defense Department noted the importance of “hedging” strategies to cope with assumption failures or unanticipated developments. Over the past 30 years, the USAF “hedged” by allocating on average two-thirds of each modernization dollar to short-range combat aircraft and one-third to long-range combat aircraft. Current plans, however, change these ratios from 2:1 to 30:1 in favor of short-range forces more dependent upon forward bases. The political  problems, logistical issues, and military threats posed to forward air bases individually raise challenges, but the uncertainties and risks induced by all these factors together in future conflicts suggest that the Defense Department leadership should re-evaluate these plans to meet the goal of projecting decisive power promptly in future anti-access environments.

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