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Asymmetric Missile Threats Loom on Horizon

October 2005
By Robert K. Ackerman
E-mail About the Author

A Silkworm cruise missile easily could be concealed in a shipping container by terrorists who could launch it from the deck of a cargo vessel off the Eastern Seaboard of the United States. The country remains vulnerable to the threat of missile attack using asymmetrical means such as offshore merchant ships serving as launch pads.
Available technologies may offer a stopgap solution.

The next terrorist attack on the United States mainland might take the form of conventional missiles carrying weapons of mass destruction. These missiles could be launched from a number of different offshore platforms or basing systems that would give citizens in coastal cities almost no warning before impact. Either cruise missiles or short- and medium-range ballistic missiles, which are easily obtainable in the global weapons market, could be used to inflict untold devastation on any of the 75 percent of the U.S. public that lives within 200 miles of the nation’s coastline.

The severity of this threat is debated within the intelligence community. Some segments view it as a potential threat but believe that al-Qaida and related terror groups are more likely to expend their resources in other areas. Others view it as a real threat that could materialize at any time.

However, little dispute exists about the capability and the U.S. vulnerability to this type of attack. A June 2003 Heritage Foundation homeland security research report describes how an enemy easily could adapt a short-range missile such as a Scud, a cruise missile or even an unmanned aerial vehicle (UAV) to be launched at the U.S. mainland from platforms disguised as commercial or private vessels just off the coast. Other analysts offer similar threat assessments (see sidebar below).

Countering the asymmetric missile threat will require a multifaceted approach. The equipment and systems needed to build an adequate defense either are available today or are in the development pipeline. And, one recently refined technology uses commercial radio and television broadcasts to rapidly detect and track these types of missiles in time for active defense measures.

National Security Presidential Directive (NSPD)-23, which was issued in December 2002, focuses on a national policy on ballistic missile defense. It states that the contemporary and emerging ballistic missile threat is far different from the one faced from the Soviet Union during the Cold War, and it requires a different set of tools for deterrence and defense. NSPD-23 also declares that, despite best efforts, the United States will face military surprises and failures of intelligence, diplomacy and deterrence.

The directive states that there is no longer any difference between theater missile defense and national missile defense. It calls for an evolutionary approach to the development and deployment of missile defenses over time. This would include deployment of additional ground- and sea-based missile interceptors and Patriot Advanced Capability (PAC)-3 units; deployment of the Terminal High-Altitude Area Defense (THAAD) and airborne laser systems; development of a family of boost-phase and midcourse kinetic interceptors based on land, sea and air platforms; enhanced sensor capabilities; and future space-based defenses.

This directive lies at the heart of proposed solutions to a rogue missile threat. David A. Kier, vice president and managing director for protection at Lockheed Martin, Bethesda, Maryland, explains that his company drew from NSPD-23 to design an architecture for defense against the asymmetric missile threat. Kier’s work in the company involves most of the defensive functions within the military and homeland defense, including missile defense; air defense; maritime defense; nuclear, biological and chemical defense; and cybersecurity.

His company’s architecture focuses on four ranges of missiles: short-range, medium-range, intermediate-range and intercontinental. Homeland defense covers all of these ranges of threats along with cruise missiles. Most of the missile defense systems being deployed by the United States today primarily are intended to counter intercontinental ballistic missiles (ICBMs) carrying weapons of mass destruction, Kier maintains. However, the nation must defend against all types and ranges of missiles, he declares.

“Anything can be made a threat to the homeland if it is mounted on a ship,” he observes. While intermediate-range missiles and ICBMs could cause major damage from land-based launching sites outside U.S. borders, short- and medium-range ballistic missiles, along with cruise missiles, could hit heavily populated areas from sea-based platforms. “A short-range cruise missile could be launched at Washington, D.C., from the Chesapeake Bay, where it would have only about 100 kilometers to travel to hit the U.S. Capitol,” Kier claims.

The consequences of any sea-based missile attack with weapons of mass destruction on U.S. cities could be devastating, both in numbers of people lost and in economic upheaval. Kier’s company used one of the Missile Defense Agency’s vulnerability and casualty models to examine potential threats according to the devastation they could wreak.

“There was no identified threat of using airliners as cruise missiles before 9/11,” Kier points out. “Our adversaries found a way to do that, and they are ‘resourceful, implacable, determined and patient,’ according to the 9/11 Commission report.”

So, Lockheed Martin engineers examined every technology available for countering any potential asymmetric missile threat. Available assets under consideration included elements in service or under development from Israel, France, the United Kingdom, Italy and, of course, the   United States. The company evaluated all of the characteristics of these defensive elements against all of the potential situations posed by asymmetrical missile attacks.

The result was hundreds of potential combinations of threats and solutions, and from this emerged the architecture embracing a mix of sensors and interceptors. Company scientists evaluated detection capabilities and interceptor response under all conditions. They also evaluated the environmental impact of potential defensive systems, especially with regard to deploying them in or near population centers.

Kier states that countering the threat requires action along three tracks. The first is to detect, identify and track attacking missiles. The second is to command and control (C2) a coherent missile defense against all levels of threats. The third is to determine which defensive weapons—both available and in development—would be employed against the asymmetric missile threat.

The company’s solution uses multiple systems to address all three functions. On the detection side, longer range ballistic missiles are readily discernible in the boost phase by existing infrared warning satellites such as the Defense Support Program (DSP) and the upcoming Space-Based Infrared System, or SBIRS. Information would be handed off to a C2 system that would fuse data, create target tracks and assign weapons for interception. Longer range missiles have a longer re-entry phase and could be intercepted farther away from their targets, which would be important if they carried a toxic payload such as a plutonium-based warhead or a chemical weapon.

Kier offers that the proposed C2 system has the ability to distinguish, track and monitor the debris field footprint from an intercepted missile. This relates to a key aspect of the C2 system. Kier explains that it must go beyond normal C2 battle management systems in its ability to interface with homeland security officials, especially first responders. It includes a substantial capability in consequence management and crisis management.

The layered defense architecture would provide the system with a choice of interceptors for each attack scenario. The key to this approach may lie in a set of tools developed by Lockheed Martin, Kier relates. Known as the predator-prey matrix, this set takes all of the systems that could intercept a missile threat and arrays them in a matrix against each incoming missile. The matrix becomes especially useful in a multiple launch scenario, enabling each defensive resource to be applied optimally to different targets or at different points in the missiles’ trajectories.

The matrix evaluates interceptor asset capabilities against specific threats, computing a probability of intercept for each. It selects the interceptor system or systems offering the highest probability of success and then allocates that asset for interception. Human intervention could change the implementation of that recommendation. Tests have shown that the entire process for solving four targets takes about 25 seconds. Two targets with three levels of defensive systems can be processed in about 16 seconds.

Sea-based defensive platforms for ballistic missiles might include an Aegis ship equipped with SM-3 missiles or even Patriots if they are installed on ships. A closer interception might feature a PAC-3. Aegis ships could work in concert with land-based interceptors. During the Iraq War, the Aegis destroyer USS Higgins provided cueing information about incoming Iraqi missiles to land-based Patriot batteries. A total of three Aegis ships could serve the entire U.S. Eastern Seaboard.

Cruise missiles and UAVs pose a different challenge than do ballistic missiles. They are more difficult to detect, and they can maneuver and take a more elusive or deceptive path to the target. These capabilities require more comprehensive detection and tracking. A look-down system would be ideal, but Kier offers that the technology to create a reliable and effective look-down tracking system currently is lacking.

This is where a theoretical technology enters reality. Many years ago, scientists theorized a way to detect air vehicles moving through the atmosphere over an industrialized populated area. The technique would involve detecting the disturbance that a metal aircraft causes on radio waves such as commercial radio and television broadcasts.

Kier relates that Lockheed Martin engineers have perfected the technology, which is known as passive coherent location, or PCL. This technology has been in existence for roughly a decade, he continues. The company has verified both theory and practice, and it is looking to conduct more operationally realistic testing.

A PCL detection system would use the radio frequency field generated by FM, ultrahigh frequency or very high frequency (VHF) radio and television stations on the periphery of the United States to betray the presence of attacking cruise missiles and UAVs. This system detects disturbances in radio fields and identifies the cause as hostile air vehicles if they are present. It may even offer a firing solution in the identification handoff to an interceptor.

Kier describes PCL as the only piece of the proposed antimissile system that is not operational today. However, he also characterizes it as the key to detecting cruise missiles. While its output is not as effective for pattern recognition or for target identification and discrimination as a good radar or infrared signature, its can be compared to existing models for identification. And, researchers have discovered that PCL works well against ballistic launches when it is based a distance away from the target.

PCL requires multiple emitters or receivers to triangulate a target’s position. Currently it can achieve three-dimensional accuracies to within hundreds of meters. Advances in broadcast technology will enhance this performance. When high-definition television (HDTV) fully replaces longtime VHF transmission, the new broadband signal will permit accuracies of within less than 50 meters. Kier relates that PCL has been demonstrated at space launches featuring the space shuttle, Titan and Atlas missiles, sounding rockets and Patriots. Even low-flying aircraft and helicopters—which Kier says stand out like a red beacon because of the Doppler effect off of their blades—have served as targets for PCL detection and tracking. Its multiple source and reception characteristics make PCL hard to jam or to spoof with conventional countermeasures.

On the testing wish list is an idea to expand PCL’s capability. Kier suggests installing FM transmitters on towers at Wallops Island, Virginia, and then placing a balloon with receivers above a ship at sea. This experiment would measure the effect of a denser radio frequency field being pushed over the curvature of the Earth.

“We have just barely scratched the surface of the potential of the system,” Kier declares.

Engineers considered employing the same approach with Global Positioning System (GPS) transmission, he adds. However, the GPS system does not have enough field strength to serve that purpose. PCL would be supplanted in 2011 by high-altitude airships or other long-endurance aerial platforms.

Kier states that the proposed asymmetric missile defense system could be deployed around some key coastal population targets within two years. However, unlimited resources and a high-priority status would be necessary, he adds.

One near-term goal for improving this antimissile architecture will require access to classified systems and data, Kier points out. The current system is based on proprietary and open-source data, but some classified government programs may offer more alternatives. At the very least, government data could modify the results of the company analysis.

The company has performed a complete analysis of the Eastern Seaboard from Boston to Washington. It has determined locations for placing transmitters, receivers, a C2 system and interceptors. The C2 system under consideration is adapted from the one being built for the U.S. Missile Defense Agency—the C2 Battle Management and Communications system, which has been operational since October 2004. It covers eight time zones from Korea to Washington, D.C., and it has operational nodes at the U.S. Strategic Command, Northern Command, Pacific Command, the agency, the White House and the Pentagon.


The Nature of the Missile Threat

Asymmetric threats are high on everyone’s clear and present danger list. Experts inside and outside government have identified many possible ways that an adversary would employ missile technology asymmetrically to deliver a weapon of mass destruction to a   populated area.

Many foreign flagged commercial ships could carry Scuds or Silkworm cruise missiles for easy launch from outside U.S. waters. Some types of dry cargo ships could launch a Scud or a Silkworm from their holds. A container ship could stack a missile-carrying container on its deck, and the missile could be launched directly from the innocuous container. A Silkworm fits neatly inside a standard shipping container. Terrorists would be able to completely launch its deadly cargo before U.S. authorities even knew that an attack was in progress. Although U.S. officials would be able to identify the culprit ship shortly after launch, this discovery would do nothing to protect the citizenry. And, if al-Qaida were operating the ship, the suicidal mentality of the organization that planned and carried out the September 11, 2001, mass murders would leave little concern about the terrorists’ capture or death after the deed is done.

In February 2004, U.S. Secretary of Defense Donald Rumsfeld related that one nation had launched a Scud from a cargo ship successfully. This was a test conducted by a nation that fired the missile into its own territory from a ship offshore. North Korea has announced a ship-launched ballistic missile with a range of 2,500 kilometers.

Many intelligence experts believe that al-Qaida already possesses a fleet of commercial cargo ships. But an     adversary need not even own a cargo ship to carry out a missile launch. Piracy is on the increase worldwide, and the means of grabbing a cargo ship on the high seas and changing its identification are well established.  In 2003 alone, 445 ships were taken. Even if a ship has all the necessary legitimate papers in hand, it still might be hiding a deadly cargo. This would defeat any vigilance that relies on a 96-hour warning.

And, al-Qaida may have dipped its toes into pirate operations on the high seas. People believed by some Asian government officials to be identified with al-Qaida pirated a 300-foot chemical tanker just outside of the Straits of Malacca, which is a notorious bottleneck for piracy. These pirates were equipped with fast boats, VHF radios and machine guns. After disabling its radio, they kept the ship, the Indonesian-flagged Dewi Madrim, for more than an hour during which they steered the ship in various directions as different individuals took turns at the helm operating it. They took money and technical documents when they left.

While some experts characterize the pirates’ actions as consistent with that of commercial piracy in that region, many local government officials fear that this was a terrorist training mission. According to one Malaysian source, the tanker’s legitimate crew, which was released relatively unharmed, told authorities that the well-organized pirates were taking pitch and roll measurements of the ship’s movement on the stern and the bow.

Another option for a ship-based missile attack would be to place a ballistic missile in a sealed tube and drop it in the ocean from the deck of a commercial vessel. The bottom of the tube, sealed off from the missile, would be weighted with ballast to achieve a specific level of buoyancy in the ocean to ensure that the nose of the missile pointed up and would barely break the sea’s surface, if at all. After an interval during which the ship would move on—perhaps to sow other encapsulated missiles offshore—the missile either would receive a signal or activate from a timer for launch against a U.S. target. The guidance system could draw its location and target bearings from the Global Positioning System. Soviet engineers practiced a canister-launch technique during the Cold War but never used it.

Or, even a land-based attack from U.S. soil is possible. A few years ago, government officials in Port Hueneme, California, intercepted a Scud B missile being delivered to a U.S. customer in the same state. Far from being a terrorist or a disgruntled citizen, the purchaser was a collector of military memorabilia. He purchased the Scud from an overseas source legitimately and legally according to U.S. laws. However, his missile, which was intercepted in its packing crates by U.S. customs officials, was not fully demilitarized by the seller as required by law. Its engine was fully functional, and it could have been turned into a weapon by fueling it and mounting a warhead of choice.

Fueling it would not have been an easy task given the deadly nature of the Scud’s regular hypergolic fuel, but a few adjustments by a rocket expert could have modified the missile to use less dangerous and more easily available fuels. The shipment that was intercepted in Port Hueneme included the missile’s complete guidance system and a transporter/erector/launcher. Properly equipped and fueled, that missile could have been set up and launched from a location in the United States to strike a heavily populated target without authorities even knowing of its lethal existence until it struck. At the very least, the ease with which a benign U.S. collector was able to purchase a deadly ballistic missile in the global marketplace illustrates the opportunities available to foreign terrorists.


Web Resources
ational Policy on Ballistic Missile Defense:
Heritage Foundation Homeland Security Research Report:
Lockheed Martin Air and Ballistic Missile Defense: