“Physics probably favors detection and the ultimate demise of stealthy systems.” So predicted the Hart-Rudman Commission in 1999. Sixteen years later, it’s time for the Department of Defense to ask tough questions about whether to continue investing scarce resources into stealth technology. Foremost among those questions is this: Are we sacrificing too much capacity in a quest for an exquisite capability, a capability that may not offer the edge it once did and whose efficacy is in decline?

Revolutionary technologies, such as the machine gun, aircraft carrier, and stealth, are characterized by large increases in performance per unit cost – gains so great they shift established paradigms. Yet, their revolutionary characteristics are ultimately transitory. The hard truth is that stealth, the cornerstone of American airpower, has entered the evolutionary phase of its development. Evolutionary technologies, which revolutionary technologies eventually become, are characterized by small increases in performance per unit cost. (For more, see Michael Horowitz’s The Diffusion of Military Power and Clayton Christensen’s The Innovator’s Dilemma). In fact, evolutionary technologies demonstrate diminishing returns along the investment curve. In the case of stealth, the initial generation of aircraft represented a massive performance increase over existing, non-stealth platforms. However, as the technology matured, continued investment began to see decreasing performance gains and therefore advantage per unit cost.

This declining return on investment is accelerated by the emergence of anti-access/area-denial (A2/AD) networks creating lethal, sensor-fused operating environments that dramatically raise the threat faced by aircraft. While advanced stealth aircraft will continue to be able to operate in that environment, there will be increasing limitations on such operations. These limitations have been driving calls for a high end UCLASS to operate inside of denied zones. This declining efficacy calls into question continuing investments aimed at fielding a fleet of stealth combat aircraft. For a sense of scale, the Department of Defense will have invested approximately $600 billion (in then-year dollars) in the development and acquisition of four different stealth aircraft: the F-22, B-2, F-35, and LRS-B (assuming LRS-B costs do not rise and ignoring lifetime sustainment costs which are higher than for non-stealth aircraft).

The first Gulf War trumpeted the arrival of stealth aircraft. Stealth, the combination of specific design configuration and absorptive coatings to greatly limit an aircraft’s radar cross-section (RCS), is a remarkable example of a qualitative U.S. military advantage. The past successes of this technology are manifold: it offset the numerical superiority of the Warsaw Pact forces; it allowed the U.S. to gain air superiority over Iraq during the First Gulf War; and it permitted the United States to penetrate Pakistani airspace and conduct the raid that killed Osama bin Laden. An almost unblemished record of success has created a mystique around this technology. Stealth has been the trump card on which American air dominance has staked its claim. Other nations have seen the value in stealth—both in having it and defeating it—and are playing catch-up. China, Russia, Japan, the United Kingdom, and France are all pursuing some type of stealth aircraft. The United States will rely on this technology to give it the edge with its next generation of combat aircraft, including the F-22, F-35, and LRS-B.

The scientific breakthrough of stealth has undoubtedly shifted the airpower paradigm, but the threats to stealth technology are shifting, as well—at a rate that is exceeding the pace of stealth technology development. The most prominent example occurred in 1999 when an F-117 was lost over Yugoslavia to a Soviet surface-to-air missile system from the 1960s. The commander of the unit responsible for the shoot down claimed that tactics and radar modifications enabled the detection of the aircraft for short periods. Since 1999, stealth technology has not advanced at the same rate as sensors, networks, and computing power. This suggests that savvy adversaries are able to challenge American stealth capability, particularly when enabled by increasingly advanced A2/AD networks.

New developments in existing technologies are paring back the stealth advantage. From a technical standpoint, stealth aircraft are primarily designed to defeat radars operating at higher frequencies, such as the X (8-12 GHz) and S (2-4 GHz) bands, as they are the most common bands for target acquisition. They are far less effective against low frequency radars such as those in the VHF (30-300 MHz) or UHF (300Mhz-3GHz) bands. Lower frequency radars have not seen greater use as they offer poor resolution and are unsuited for fire-control and terminal guidance. However, new technologies are increasing the resolution of low-frequency radars, which in turn reduces stealth’s advantage. In fact, Russian arms maker Almaz-Antey has been marketing a VHF radar with “counter stealth” capabilities, and China just announced a UHF radar with similar claimed capabilities.

Additionally, technological advances such as networked, active electronically scanned arrays and advanced signal processing systems may “overwhelm the capacity of aerospace engineers to reduce platform signatures.” It is not only improved radar technology that is eroding the stealth advantage; improved thermal sensors and other optical change detection systems may offer additional methods for defeating stealth technology. Furthermore, increases in networking technology and advances in computer processing mean that this data is able to be collected, analyzed, and disseminated faster than ever before.

This is not to say that stealth will lose its value overnight. It will continue to offer protection against many forms of detection. Some argue that stealth performance has improved in comparison to first generation systems, such as the F-117, and high maintenance costs have declined. While this may be true to some degree, operational costs remain considerably higher than for comparable non-stealth platforms. In addition, aircraft able to defeat the “exotic” radars that claim to counter stealth technology must have certain design configurations that increase platform complexity and inflate development and testing costs. The B-2 is a perfect example of the challenges imposed by the non-traditional configurations necessary to defeat a broader array of radars.

The problem, then, is one of cost imposition, with protection costing substantially more and taking longer to develop than the emerging technologies designed to counter it. Given what we think we know about the future security environment, it may be time to consider alternatives to and complements for this 25-year-old technology. A less expensive, more flexible alternative would see the U.S. commit to a high-low mix heavily weighted to cheaper, non-stealth platforms. The lifetime cost savings reaped from such an approach would enable a greater number of total aircraft to be fielded than would be possible with an all-stealth fleet of tactical aircraft. At the lower end of the threat spectrum, a force mix weighted toward non-stealth platforms provides greater capacity for dealing with simultaneous global contingencies and reduces operational costs while retaining lethality.

This mix would leverage advances in precision weapons and allow the United States to retain a standoff, penetrating strike capability. In addition, a new generation of low cost, reusable, and ultimately disposable unmanned systems can help invert the cost imposition of A2/AD networks by overwhelming an enemy’s ability to engage at favorable cost exchanges. In this paradigm, the United States would retain a small nucleus of exceedingly capable stealth systems for striking the most protected targets, achieving and maintaining air dominance, and providing C4ISR (Command, Control, Communications, Computer, Intelligence, Surveillance, and Reconnaissance) and information warfare capabilities in denied zones. Against the most capable adversaries, initial airspace penetration by stealth platforms, stand-off munitions, and disposable systems would be complemented by targeted cyber and electronic warfare operations against key adversary nodes. This high-end warfighting concept for integrated employment of airpower creates asymmetries through non-kinetic degradation, saturation of adversary engagement capability, and targeted kinetic effects. This concept closely resembles the swarming proposal put forward by John Arquilla and David Ronfeldt in 2000.

Deepening the commitment to stealth, a 25-year-old technology, for the next 30 to 50 years is not wise given the rapid pace of technological advancement. Ultimately, overinvestment in technologies that deliver marginal improvements at high costs will not allow the U.S. to maintain its technological overmatch in the coming decades. By exploring alternatives and complements to stealth systems as discussed above, the U.S. would regain the first mover advantage that it enjoyed when stealth was introduced.

Andrew Metrick is a research assistant with the International Security Program at the Center for Strategic and International Studies. His work has covered a broad range of issues, including maritime forces, emerging technologies, and unmanned systems.

Photo credit: Official U.S. Navy Imagery