Friday, June 2, 2023

Terrorists Attack: Port Of New York

South Street Seaport Fire 2012. Photo by Jane Kratochvil

This story was republished with permission of Captain Joe Skinner, U.S. Navy (Retired) and Proceedings Magazine, the flagship magazine of the U.S. Naval Institute.

Yesterday morning, terrorists used the Kuwait-flagged merchant vessel Umm Salat—a commercial ship loaded with more than 10,000 shipping containers—to attack New York Harbor just as the U.S. Navy’s Fleet Week began. After the harbor pilot boarded the ship, the crew revealed its intentions to him—to conduct a suicide attack. The ship increased speed to flank and aimed for the largest Navy ship in the harbor. Prior to the collision with the USS New York (LPD-21) the terrorists opened and dumped dozens of containers overboard, dispersing hundreds of naval mines into the water, completely seeding the harbor. The impact of the Umm Salat with the New York effectively destroyed and sank both ships. Explosives detonated in shipping containers on the bow of the Umm Salat killed hundreds of Navy sailors and civilians who were touring the New York or waiting on the pier. The Port Authority of New York and New Jersey immediately halted all shipping into and out of the port while mine clearing operations commenced.
This scenario may be unlikely, but it is possible. Terrorists have used vehicles as attack mechanisms so often that the military created the acronym “VBIED,” for vehicle-borne improvised explosive device. On 9/11, commercial aircraft were the weapon of choice. In Iraq and Afghanistan, suicide bombers have used cars lled with explosives to kill U.S. military personnel and civilians. Recently, terrorists used trucks to run down pedestrians in France and Germany. Is it just a matter of time before they turn a large commercial ship into a VBIED and attack a major port? In March 2003, pirates boarded the chemical tanker Dewi Madrim near Sabah in the South Pacific for several hours. Their intention was not to ransom the crew or steal its cargo, as pirates usually do, but to learn how to steer it. (*M. Ijaz, “The Maritime Threat from Al-Qaeda,” Financial Times, 20 October 2003, 21.)
In addition to the ship-as-VBIED threat, terrorists employing naval mines from a commercial ship also is a plausible scenario. Naval mines are one of the least expensive and most effective threats to ships. They would not be difficult for terrorists to acquire. Iran’s navy has several thousand mines, and the U.S. Department of State lists Iran as the number one state sponsor of terrorism. (*Sydney J. Freedberg, “Sowing the Sea with Fire: The Threat of Sea Mines,” Breaking Defense, 30 March 2015, The presence of mines alone could cause a port to be closed for days or weeks as mine countermeasures were deployed to sweep and clear the harbor.
There are three ways to defend against a ship attack against a port: prevent the attack; maximize the distance between ship detonation and vital infrastructure; and shield the vital infrastructure. Prior to entering U.S. ports, all ships are evaluated as part of the U.S. Coast Guard’s advanced notice of arrival (ANOA) process to determine the relative potential threat to the port.

Navy ships in port as well as maritime infrastructure could be lucrative targets for terrorists using a large ship as a VBIED. Here the USS New York (LPD-21) enters New York Harbor in 2009. (U.S. Navy photo by Chief Mass Communication Specialist Eric M. Durie/Released)

If an attack cannot be prevented, measures should be taken to maximize the distance between vital city areas and the threat. The first line of defense would be designed to keep threats away from shore. For high-risk ships entering port, for example, a defensive ship with adequate mass could station itself to block passage. In addition, tugs could be used to engage the ship. Jim Murray, a senior executive of a tugboat company that operates in numerous U.S. ports, noted the Port Authority of New York and New Jersey considered the use of tugboats to stop a large merchant ship but quickly realized they would have little effect. “At any speed at all, above ve or six knots at the most, it would be nearly impossible to alter a vessel’s course with a tug. Any higher speed and the tug would just slide down the side of the ship and perhaps capsize.” Instead of blocking a ship, tugs could be used in an asymmetric manner. Defensive tugs could be armed with a harpoon launcher to pierce the hull of a rogue ship, near the waterline in the engine room. An expanding arrowhead designed to pierce thin hulls could then rip the side of the ship open if the harpoon was pulled down and toward the stern of the ship. The harpoon could be attached to a line with sea anchors and a danforth anchor to provide the pulling force to slow a ship and tear a hole in the hull. A swarm of attack tugs should be able to disable a ship by ooding the engine room. At a minimum, a rogue ship’s speed would be reduced, limiting its ability to penetrate a port’s layered protective barrier system.
Another alternative to maximize distance is to employ rock or chain barriers. Tetrapods—concrete devices that loosely interlock when piled up—are one of the most effective methods to prevent shoreline erosion. To provide stand-off, tetrapods could be placed 100 yards from a quay wall, completely encircling the port. They could be piled underwater until ten feet below the surface, allowing small boats and ferries to pass freely while stopping deep-draft, oceangoing ships. The barrier would have a limited number of deep-draft entrances to piers, which could be arranged to force a ship to stop and pivot 90 degrees from the channel to line up with the pier. A large ship at any speed above five knots would not be able to make such a turn.
During the Revolutionary War a chain across the Hudson River blocked the passage of British ships at Fort Arnold (now West Point). A similar but more devastating design could be used for port security today. A heavy chain could be modified to incorporate cutting edges seen in wire saws. Such a “maritime chainsaw” could be placed at a shallow depth so it would hit a ship just above the bulbous bow found on modern merchants. The chain would block the deep-water piers and be lowered only for properly cleared ships. It would be secured tightly on one end, and the other end would remain in heavy tension, secured by a mechanism that could pay out the chain either to lower it, providing access to the piers, or feed slack when a ship collides with the chain. This feeding action would create a cutting force between the maritime chainsaw and the attacking ship’s hull.
Barriers on the pier could form another protective measure. Retractable barriers and crumple buildings used together could protect people and infrastructure at the port from explosive blasts. The best protection would be large structures with significant mass to block the kinetic energy from a blast. Modern cities, however, are unlikely to sacrifice scenic views for security. In the past 15 years there have been significant advancements in military blast protection. Many of these developments are not applicable to civilian port protection because of cost, maintenance requirements, and shelf life, but retractable steel barriers provide significant protection at a reasonable price. A retractable steel louvered design uses strips of overlapping steel similar to the louvers in house blinds. When a blast hits such a barricade, low-level blasts are blocked while larger blasts are diverted upward through the louvers, which maintain a shadow zone to protect people and critical infrastructure behind the barricade. The added benefit of louvered barriers is they also could protect a city from up to a ten-foot storm surge.
Buildings on or in the immediate vicinity of the quay wall could be designed with blast crumple zones. These barrier buildings could use a design similar to that of modern automobiles. Upon impact a car’s outer body crumples, absorbing much of the energy from a crash. Energy dissipation prevents the driver from experiencing the full force of the accident and saves his or her life. Similarly, barrier buildings could be designed with crumple zones that would crush inward but not violate a building’s structural integrity when exposed to explosive blast energy. If done correctly, blast energy could be directed away from people working in the buildings.
The Container Security Initiative was announced by U.S. Customs and Border Protection (CBP) in 2002 and has improved the nation’s security by checking containers prior to their entry into the United States. (*U.S. Customs and Border Protection, “Container Security Initiative In Summary, 2011,” However, only a small portion of containers entering U.S. ports are searched. “CBP currently scans 3.7 percent of the roughly 11 million containers entering the United States each year. About 1 percent of that total, or 104,000 exams, are checked at overseas ports.” (*Gruenert Hans, “U.S. Lawmakers Say With New Technology, It’s Time to Inspect All Inbound Containers,” Westar, 24 August 2016, This number is far below the 100 percent check mandated by Congress in the Implementing Recommendations of the 9/11 Commission Act of 2007.
The Department of Homeland Security is focusing on advanced technology solutions, but it is difficult to transfer many of these advanced and expensive technologies to the conditions in a working port. One simple solution could be weighing and tilting a container. All container loads are recorded on shipping documents, so the contents and weight of the container are known. It would take minutes to attach accelerometers and weigh each container. A scale would be able to determine if the weight is distributed as expected for the load listed on the manifest. Tilting each container side-to-side and along its length would tell if the expected load is in the container. Any container with abnormal characteristics would receive further screening. To minimize costly time delays, an alternative and faster method to weigh and tilt containers could be incorporated into the lifting harness, allowing containers to be tested while being onloaded to a ship.
Merchant ships have been used to deliver mines in the recent past. In 1984, the Libyan ship Ghada was suspected of planting the mines that damaged at least 17 ships in the Gulf of Suez and the Red Sea. (*Judith Miller, “Red Sea Flotilla Crosses the Canal,” New York Times, 16 August 1984, Mines are one of the cheapest and most available weapons to deploy against a port. During the first Gulf War, the USS Tripoli (LPH-10) and the USS Princeton (CG-59) were damaged by mines, and Kuwaiti ports required sweeping to allow a path for seaborne supplies. (*Eric Schmitt, “Gulf Is Swept for Mines in the Aftermath of War,” New York Times, 19 March 1991,
The clearance of mines is difficult. Floating mines, described in the New York City scenario, could be collected on the surface of the water or destroyed. Bottom mines are more difficult to find and neutralize and normally would be destroyed in place. If bottom mines were deployed in a port like New York City, the infrastructure on the bottom or buried in the bottom of the harbor could preclude destruction in place. For example, it would unwise to destroy a mine sitting on top of the Holland Tunnel.
The best way to counter mines in a harbor is to prevent them from being planted, which requires extensive intelligence and screening of ships prior to entering port. The next best option is to have a comprehensive removal plan in place. Such plans require detailed bottom maps of U.S. harbors to support mine detection. All port authorities must know what infrastructure is on the bottom of their harbors and what critical waterway passages must be restored. These two lists would assist in prioritizing the order that mines would be cleared.
The shear size of the U.S. marine transportation system presents security challenges. In many locations sinking a ship in the main channel could shut down a harbor for months. For the largest harbors in the United States, a ship sunk in a channel might not completely block the harbor but would be an annoyance until removed. A more important question, however, might be why the obstruction was placed in the channel. Did terrorists want to create an annoyance or is the ship a single, large, stationary mine waiting for an unsuspecting target?
Terrorism is a reality today. We should anticipate attacks and develop countermeasures that eliminate or mitigate their impact. The ability to destroy critical port infrastructure, kill large numbers of people, and shut down commerce by using a large ship as an attack vector could be very attractive to terrorists. The Department of Defense and the Department of Homeland Security should not wait to act. All suspect ships should be treated with the gravest concern until they are inspected and cleared. The defenses described here would harden the country’s port infrastructure and minimize the likelihood and the impact of a maritime terrorist attack in a major U.S. port city.

Secretary of Defense Chuck Hegel and Capt. Joe Skinner

CAPTAIN SKINNER was a career submariner who commanded the USS Louisville (SSN-724). He later served on the U.S. Pacific Fleet and U.S. Pacific Command staffs, working on U.S. naval and military strategy and policy in Asia. After retiring from the Navy, he worked in the Office of the Under Secretary of Defense for Policy, where he developed a long-range cooperative security strategy for Taiwan. He now lives in Oxford.