Distributed Sensing: The Key to Successful Air And Missile Defenses

by Dan Goure

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For more than two centuries, the U.S. military has practiced a particular style in warfare, which some have called the “American Way of War.” This method tends to focus on attrition and annihilation. It depends on the creation of material superiority on the battlefield which, in turn, relies on economic advantages relative to adversaries. Today, the return of great power competition centered on the proliferation of advanced military technologies has put in doubt the ability of the U.S. to execute its preferred methods of warfare. If the U.S. is to be successful at deterring and winning conflicts, its military will have to change both how and with what it will fight. A key aspect of that change is the exploitation of opportunities for distributing sensors across all domains.

U.S. military leaders, both in and out of government, recognize that for the first time in three decades, this country could lose a large-scale conventional conflict. The U.S. and its regional allies are now confronted by potential adversaries who have spent decades investing in a set of integrated capabilities specifically for the purpose of denying the U.S. the ability to conduct high-end conventional warfare at the time and place of its choosing. Potential adversaries have deployed long-range precision strike systems, intended to attack high-value platforms and the limited set of major facilities housing and supporting U.S. and allied forces.

The U.S. military is seeking to restore its erstwhile advantages in high-end combat by changing the ways it conducts offensive and defensive operations. Simultaneously, it is looking to enhance the lethality and survivability of its formations and platforms without having to mass forces. This involves in part, making individual platforms and units more effective through the deployment of advanced, long-range precision strike capabilities. It also involves the introduction of advanced defenses against airborne, ballistic and space-based threats.

The Department of Defense is working hard to develop the sensor grids, network and command and control capabilities to support an information-intensive American Way of War. Ultimately, the goal is to be able to connect any sensor to any shooter in a way that enables commanders to employ the best shooter for engaging a target.

Creating proliferated and integrated networks of sensors will be particularly important for successful air and missile defenses. Great power competitors and regional powers have invested in air-breathing weapons and ballistic missile systems intended to hold U.S. forces and bases at risk from the outset of a conflict. The U.S. military cannot hope to outguess these adversaries with respect to when and how they might choose to attack. Instead, it must have a sufficiently robust and distributed system of sensors and weapons to respond rapidly to any attack.

At present, the U.S. military suffers from problems with holes and blind spots in its traditional surveillance architectures to support a robust air and missile defense capability. The system is largely reliant on a small set of large, fixed radars.

The evolving air and missile threat in the Pacific provides an instructive example of the problem. Defense of Pacific islands has become a priority in the U.S. National Defense Strategy. But the current set of radars, oriented more to defending the U.S. homeland from attacks by North Korea, Russia and China are not adequate to meet complex threats launched from multiple azimuths. This problem is exacerbated by the development of hypersonic missiles that shorten the time available for radars to detect the threat. The commander of the Indo-Pacific Combatant Command (USINDOPACOM) has made the development of a 360-degree integrated air defense capability in Guam his number one unfunded priority. There is a similar problem using the current set of radars and interceptors to defend the Hawaiian Islands and U.S. allies such as Japan, South Korea and Australia. Military planners are in agreement that what USINDOPACOM requires is a proliferated system of sensors.

The realities of geography and the kinematics of missiles and airbreathing platforms means that this problem cannot be fixed by building more large, expensive land-based sensors. Future operations, including integrated air and missile defenses, will need to have a sensor architecture that provides real-time global tracking of hostile forces and platforms. This should be available from space if possible, but also from land and sea-based sensors as necessary.

The best way to provide the most adequate global surveillance is from space. The Missile Defense Agency has been given responsibility for developing the Hypersonic and Ballistic Tracking Space Sensor (HBTSS), a proliferated array of low orbiting satellites that will provide birth-to-death tracking of objects in space, in the atmosphere and on the Earth’s surface.

But the HBTSS is many years away from being deployed. In the meantime, a distributed air and missile defense layer based on smaller, less costly radars could be built to supplement the existing systems and provide enhanced surveillance and tracking of ballistic and air-breathing threats. Smaller, relocatable land- and sea-based radars can be deployed in greater quantities to improve coverage, particularly against low-flying threats. By operating cooperatively, these smaller radars can provide equivalent coverage to large, fixed-site radars. Moreover, these sensors could be relocated to respond to evolving threat conditions.

The U.S. Navy has developed a distributed air and missile defense capability centered on the Aegis ballistic missile defense system. A ground-based variant of this system, Aegis Ashore, is being deployed in Europe and was until recently planned for deployment in Japan.

Adding smaller land- and sea-based radars to the existing constellation of large, fixed radars has many benefits. One is improved performance. A larger distributed set of radars can close gaps in global coverage, increase the system’s overall l sensitivity and range, and provide additional viewing geometries to improve tracking and discrimination.

Another benefit is greater resilience in the face of adversaries’ efforts to attack the sensors themselves. A distributed sensing system will have greater survivability and degrade more gracefully under attack. Coverage can also be maintained even when a particular sensor is down for maintenance or repair.

Adding a set of smaller, less costly radars to existing networks in the Pacific, Europe and the homeland could create an effective distributed sensor architecture. This investment would be an important step along the path to creating a robust air and missile defense capability.

Dan Gouré, Ph.D., is a vice president at the public-policy research think tank Lexington Institute. Goure has a background in the public sector and U.S. federal government, most recently serving as a member of the 2001 Department of Defense Transition Team. You can follow him on Twitter at @dgoure and the Lexington Institute @LexNextDC. Read his full bio here.