March 1, 2008  

Undersea warfare: The hidden threat

Sunday, Sept. 11, 2011, passed without incident. New Yorkers breathed a sigh of relief, as did most Americans who were glad there were no terrorist attacks since that fateful day 10 years ago. The Department of Homeland Security was now well-established and doing a better job securing air travel and our borders against terrorists. Polls indicated that most Americans felt secure.

Ironically, it was precisely that improved security that drove al-Qaida to seek new ways to attack America, something that proved elusive since the U.S. drove the group and their Taliban hosts from Afghanistan. Several years before, al-Qaida leaders heard about narcotics cartels smuggling drugs into the U.S. using small submarines. Because enhanced airport and border security made traditional infiltration paths too risky, al-Qaida considered using submarines and other vehicles as a means to attack the U.S. Over the next few years, the terrorist network planned to strike U.S. economic infrastructure to inflict more severe harm than the damage done in 2001.

Monday, Sept. 12, 2011, began as another quiet day, but about 10 a.m., workers on Wall Street were among the first to realize something was wrong. Internet speeds had slowed considerably and they couldn’t access overseas sites.

In Northern Virginia, watch officers in the Pentagon’s National Military Command Center were having trouble communicating with units outside the continental U.S. The military leases bandwidth from the same telecommunications companies that support commercial traffic, and they occasionally experience outages. However, the military has priority, so this prolonged interruption was unusual.

Farther south, in the Gulf of Mexico, workers aboard the massive Thunder Horse oil production platform were surprised by lowering pressure in seabed pipelines that sent oil from deep sea wells to onshore facilities. To the east, utility workers in Tampa, Fla., were similarly puzzled by falling pressure in the Gulfstream natural gas pipeline. That pipeline runs hundreds of miles on the seabed between Alabama and Tampa Bay, where it comes ashore and supplies much of Florida’s natural gas needs.

What none of these workers realized is that the U.S. was under attack. Over the past year, al-Qaida used a combination of merchant ships, commercial submarines and remotely operated vehicles to place explosives in U.S. ports and adjacent to seabed infrastructure, including transoceanic telecommunications cables, and oil and gas pipelines in the Gulf of Mexico.

At about 10:30 a.m., the second phase of the attack was initiated. Over the next hour, terrorists surfaced small submarines in New York Harbor and Galveston Bay. These submarines were towed by inbound commercial vessels the night before and waited on the bottom for the appointed time. Once on the surface, terrorists released floating mines and launched shoulder-fired missiles at loading facilities, ships in port and an oil refinery.

Just as it was singled out 10 years earlier, New York City was again a major target. Missiles severely damaged the Verrazano-Narrows Bridge while explosives placed a few days earlier flooded the Lincoln, Holland and Midtown tunnels. Manhattan wasn’t completely isolated, but capacity on the remaining crossings would be inadequate by any measure. In a parting shot, one submarine motored to a West Side pier, where the suicidal pilot detonated a dirty bomb, spreading radioactive contamination over a wide area.

As reports of the attacks spread, world financial markets went into a tailspin led by skyrocketing oil and natural gas prices. The Securities and Exchange Commission quickly terminated stock and commodity trading while authorities grounded all commercial aircraft, closed ports and stepped up security at key facilities, such as nuclear power stations.

By 2 p.m., telecommunications companies determined that most seabed fiber-optic cables serving the U.S. were inoperative. Later in the evening, energy companies confirmed that sections of the seabed oil and gas infrastructure in the Gulf of Mexico had been destroyed, two production platforms were in danger of sinking, and an oil refinery on Galveston Bay was heavily damaged, with fires still raging out of control. While congressmen and media pundits blamed yet another intelligence failure, government agencies wondered why they hadn’t uncovered this plot. Perhaps hints of an undersea attack were dismissed as too difficult or sophisticated for al-Qaida.


This fictional attack dramatizes the real difficulty in protecting our growing but vulnerable undersea infrastructure that is vital to our economic prosperity. The undersea realm is perhaps the last sanctuary on earth because of our inability to see in that hostile medium. In recent years, access to that environment has been facilitated by a growing array of commercial submarines and remotely operated vehicles. Together, these trends provide greater opportunities to use the sea for legitimate purposes, but they also enhance our vulnerability to attack.

Why attack from under the sea? The short answer is stealth. Stealth provides sanctuary from detection and prosecution. Unlike aviation stealth, which requires highly sophisticated and expensive aircraft, nearly any vehicle operating under the sea is extremely difficult to find. Whereas radars can scan thousands of square miles of air space and do so continuously, there is no equivalent system underwater. No one is watching the undersea approaches to the U.S. or checking the seabed along the continental shelf for nefarious activity. There is no undersea analogy to the no-fly zone designed to protect critical airspace.

The ability to “see” underwater requires high-frequency sonar systems or lasers that can provide sufficient resolution to identify objects such as mines and cables. However, these systems have short ranges, making large-area surveillance extremely difficult. Passive sonar is useful to an extent but relies on detecting noise from mechanical apparatus such as submarine propulsion systems. Although some large passive sonar systems such as the Sound Surveillance System were effective in detecting older Soviet submarines, newer submarines have such low sound signatures that they are extremely difficult to hear. Small commercial submarines, remotely operated undersea vehicles, seabed habitats and, of course, explosive packages have such small or nonexistent sound signatures that detecting them passively is nearly impossible. Add to that high levels of background noise in ports and littoral regions, and the problem is compounded.

The stealth afforded by the sea — even for unsophisticated users — infers several advantages that al-Qaida leveraged in the fictional attack above. First and foremost is the ability to operate in close proximity to an adversary’s territory without being observed. Just as U.S. submarines have done for years, al-Qaida operatives would have been able to conduct reconnaissance and other operations with little risk of being discovered.

Surprise is a second major incentive to attack from under the sea. A major advantage U.S. submarines enjoy is the ability to strike adversaries quickly and with surprise from close-in positions. Al-Qaida could do the same thing, albeit on a smaller scale: It could engage shore targets with short-range missiles from point-blank range. The surprise nature of the attack would reduce our ability to adopt defensive postures or to relocate high-value systems or personnel.

Stealth also maximizes economy of force. It allows a smaller number of operatives to place explosives or weapons in multiple locations over an extended time frame and later conduct coordinated, simultaneous strikes at a time of their choosing. Multiple, simultaneous strikes would tax our defensive and consequence management capability. Also, a small force might be especially attractive to al-Qaida because it would minimize the operation’s footprint, making it harder for intelligence agencies to uncover.

Another incentive to attack from under the sea is the ability to circumvent U.S. defensive measures. As more effective ballistic and cruise missile defense systems come online, competitors will seek asymmetric methods of attack instead of facing those systems head on. Although disrupting telecommunications cables and energy infrastructure may pose grave economic consequences, other uses of the seabed could present even greater security challenges. For instance, a state adversary with more sophisticated covert delivery capabilities, including merchant ships with false bottoms, could stage encapsulated missiles on the seabed along the U.S. coast. When triggered, they could strike U.S. cities and military installations with very short flight times, making interception unlikely. Also, current treaties notwithstanding, nuclear weapons could be detonated on the seabed to damage or destroy ports and coastal cities. Major U.S. investments in missile defense systems could be offset by such strategies. Moreover, a high percentage of the U.S. population and much of its industry are within a short distance of the coastline. Attacking these regions would be highly disruptive. But that isn’t the case for every nation. Some countries don’t have major coastal cities and might find this a useful asymmetry to exploit against the U.S.

A final incentive is the imposition of a cost-imposing strategy. After Sept. 11, the U.S. created the Transportation Security Administration and instituted draconian air-travel security measures. These new procedures enhanced security, but they also robbed millions of travelers of their time, increased the cost of air travel and reduced overall productivity. Add to that increased security for other modes of transportation, public buildings and facilities, and the cost keeps rising. Al-Qaida only needs to carry out one successful undersea attack to impose even greater security costs on U.S. citizens before moving on to the next soft target.


Seabed communications cables have been around since the 19th century, but early systems provided limited bandwidth and unreliable service. In the mid-20th century, satellites provided an alternative source of long-range telecommunications, but they were expensive, and their bandwidth was limited. Space systems remain expensive, but since the 1980s, advances in fiber-optic technologies have enabled new undersea cables to surpass satellite capacity and compete for global telecommunications, especially as the Internet expanded. Today, even communication networks that start with satellite systems (such as ships at sea) often are dependent on seabed cables to connect satellite ground stations with end users. Seabed cable systems now crisscross the world’s oceans and support the majority of international telecommunications to and from the U.S., including government and military traffic. These systems could become the focal point of future nation-state conflicts, as well as prime targets for global insurgencies.

A chart of transoceanic routes shows many cables spanning thousands of miles. It might dissuade potential adversaries from attacking the system because it appears so large. However, many of those cables are dark or unused. New cables have such tremendous capacity that they replace numerous older ones, concentrating a large percentage of overall bandwidth in a few major cable systems. Also, to minimize fishing restrictions along our coastlines — fishing activity represents a major hazard to seabed cables — cables come ashore in only a few places. Termination points near Manasquan, N.J.; Shirley, N.Y.; and Miami have high cable concentrations, making those areas likely targets. The locations of these cables are specifically highlighted on public charts to help fishermen and other mariners avoid them. Consequently, a limited effort would be required to disrupt a major percentage of U.S. transoceanic bandwidth.

In late January and early February, five undersea telecommunications cables were cut, crippling Internet access across wide swaths of the Middle East and India. The cause of the damage is still under investigation, but the episode highlighted how a relatively small amount of damage to the undersea infrastructure can instantly affect millions of people.

Energy companies are also making greater use of the seabed. As terrestrial supplies of oil and gas dwindle, and political mischief such as Venezuela’s recent nationalization of oil production denies access to traditional sources, drilling operations are moving farther offshore and into deeper waters. For example, the Thunder Horse oil field in the Gulf of Mexico is 125 miles offshore and in 6,000 feet of water. Drilling in these locations requires massive floating platforms that displace more than 100,000 tons and cost nearly $1 billion. Once wells are drilled, operating costs are minimized by connecting multiple wells to a network of seabed pipelines that move crude oil to land-based refineries. Similarly, natural gas is being shipped to consumers via seabed pipelines. The Gulfstream Natural Gas System pipeline, for example, runs for 691 miles under the Gulf of Mexico from Alabama to a growing consumer base in central Florida.

Since the latter part of the 20th century, the world’s oceans have become a target-rich environment that provides adversaries with incentives to develop undersea operational competence and strike these difficult-to-defend systems.

Traditionally, there has been a high barrier to entry for anyone wanting to access deep ocean areas. Only navies or state-sponsored research organizations could fund the vehicles needed to descend and work in such a hostile environment. For the past several decades, however, access has been facilitated by the commercialization of small submarines and remotely operated vehicles (ROVs). A large number of manufacturers are selling submarines and ROVs with impressive capabilities. Small submarines capable of diving to 1,000 feet with 12 hours of submerged endurance are available for about $450,000, with even-more-capable vessels available for an additional cost. These affordable vehicles can provide stealthy transport capability for personnel and apparatus, and access to the seabed inside harbors and out to the continental shelf. Undersea ROVs with greater depth capability can be operated from surface craft of all types and provide access to most of the world’s oceans. These mainly tethered vehicles allow legitimate users to construct and maintain drilling systems at significant depths with a high degree of dexterity and reliability. This same equipment could be used to deliver threatening payloads or to disrupt seabed infrastructure. Autonomous unmanned vehicles are even more capable than their tethered counterparts and are also proliferating. They are essentially underwater guided missiles that could be used to attack targets in the ocean, inside harbors and even up rivers.


Since Sept. 11, defense planners have given considerable thought to how the U.S. might be attacked again and what segments of our society — including undersea infrastructure — might be targeted. However, much of that thinking has been conventional, with predictable recommendations to improve physical security at shore facilities and increase patrols in shallow areas where cable sabotage has traditionally taken place. Unfortunately, this analysis overvalues the past and could lead to future surprises now that access to deep ocean areas is widely available.

Altough the new Department of Homeland Security seems to be considering a broader range of attack scenarios, it still faces the same internecine conflicts that prevent well-established departments from working together effectively. Planning for and responding to an undersea attack might be particularly challenging because so many organizations will be required to participate. Coordinating action across those departmental seams was not a U.S. strong point during the response to Hurricane Katrina, and more agencies would be involved in combating an undersea attack.

Still, there are actions government planners should consider to enhance our defense. They include:

å Develop an aggregate picture of U.S. undersea infrastructure to better understand the nature and scope of our vulnerability. Elements of the infrastructure should be prioritized in terms of systems that warrant greater protection or the deployment of back-up capabilities, such as stealth communications cables for emergency government use.

å Establish a Red Team to develop plausible attack scenarios and assess their effect. Scenarios should include new technologies such as autonomous undersea vehicles that could find and disrupt seabed systems or port facilities.

å Conduct war games with representatives from appropriate agencies to highlight and resolve turf battles in advance. War game results should inform intelligence agencies about the types of systems, capabilities, operational concepts and training that could portend undersea attacks or enable an entity to conduct them. Of specific importance might be the characteristics and operating profiles of surface vessels that support undersea activities.

å Develop capabilities to monitor critical seabed infrastructure so that defensive or recovery actions could be implemented quickly. This should include an assessment of the systems needed and time required to restore services.

å Review existing treaties and protocols to determine their adequacy in light of new technologies, and whether U.S. declaratory policies would be appropriate.

å Identify technologies and capabilities that would help secure our seabed infrastructure and guard the undersea approaches to the U.S.

å Ensure U.S. submarine force structure is sufficient to conduct offensive operations worldwide to counter any adversary’s undersea strategy. The capability of the U.S. nuclear submarine fleet should give state competitors pause and serve as a deterrent to coercive or threatening undersea activities.

Extremist ideologies and the overwhelming position of economic and military advantage the U.S. enjoys provide incentives for adversaries to seek asymmetric means to attack our interests. As the U.S. develops more effective counters to conventional strike capabilities, such as national missile defense systems, our adversaries will continue to adapt. Defense planners should carefully consider all avenues from which the U.S. could be attacked and avoid the rigid mind-set that blinded us to the methods used on Sept. 11. The oceans remain one of the only frontiers in which humans cannot see clearly. Exploiting that frontier could provide adversaries with sanctuaries from which they could attack the U.S. economically or militarily, with little or no warning.

Karl M. Hasslinger is a retired Navy captain and former submarine commander with strategic planning experience on the Chief of Naval Operations staff and in the Office of the Secretary of Defense. He is director of Washington operations for General Dynamics Electric Boat.