On 15 February 2012 an Italian security team onboard the oil tanker MV Enrica Lexie off the coast of southern India shot two innocent local fishermen whom they suspected of being pirates. This not only led to a diplomatic row between India and Italy, but once again, sparked a debate about the security of shipping and the use of armed guards (in this case a military protection team). This debate largely focuses on Somali, and increasingly West African, piracy and the difficulties experienced in eradicating this threat. However, the security issues related to shipping are not limited to piracy; there also exists the risk of maritime terrorism, or terrorism committed in the maritime domain, which could potentially have an even bigger impact than piracy.

Experts have thought of many scenarios. Terrorists could assault ships as an “iconic” goal, or attack ships and offshore installations to damage the economy, they could target ferries to cause mass casualties or use ships as weapons to attack other ships or ports (Martin N. Murphy, Contemporary Piracy and Maritime Terrorism (2007) 55-61) Security experts have also pointed to the possibility of maritime terrorism with Chemical, Biological, Radiological or Nuclear (CBRN) agents. This report assesses the threat of maritime terrorism, with a special focus on CBRN agents, by providing an overview of the possible perpetrators of maritime terrorism and their respective objectives, and by investigating the feasibility of several scenarios.

Maritime terrorist organisations

The threat of “maritime terrorism” is far from new. As an example, the 1985 hijacking of the cruise ship MS Achille Lauro by four members of the Palestine Liberation Front (PLF) even then demonstrated the potential risks to shipping with just a few assailants. Nevertheless, one could argue that maritime terrorism is, so far, a relatively small problem. The number of past incidents is limited, even when one includes attacks against military targets (such as the al-Qaeda attack on the USS Cole, discussed below) which would not be considered terrorist attacks in the strict definition of the word. Moreover, there have until now been no maritime terrorist incidents which involved the use of CBRN materials. However some government officials and experts believe that this could change, perhaps because of improved inland security measures and the relative ease with which some scenarios involving maritime terrorism could be carried out (Greenberg et al., Maritime terrorism. RAND, 15). These officials and experts are strengthened in their conviction by the fact that terrorist organisations have conducted ambitious attacks at sea, proving that it is certainly feasible that terrorist organisations would be able to carry out more far reaching operations in the future.

At sea the most effective terrorist group has arguably been the Tigers of Tamil Eelan (LTTE), or “Tamil Tigers”, who operated a naval wing under the name of the “Sea Tigers”. This encompassed a small fleet of speed boats, which were used with considerable success in “sea guerrilla” warfare against the Sri Lankan navy. The successes of the Sea Tigers allegedly inspired al-Qaeda to attack the U.S. Navy destroyer USS Cole with a small craft loaded with explosives in the Port of Aden in Yemen in October 2000. This resulted in the death of seventeen American sailors.

Less well known, but also potentially very dangerous,was the attack claimed by al-Qaeda on the French flagged very large crude carrier Limburg, when anchored off the coast of Yemen in October 2002. The Limburg was rammed by a small boat packed with TNT. The resulting explosion blew a hole through the double hull of the ship and started a fire. One crew member was killed, twelve were injured and oil started leaking from the ship. The modern design of the Limburg and the inert nature of the gas fumes inside prevented a more dramatic impact.

Also for the future, al-Qaeda is assessed to be one of the most likely candidates to be involved in maritime terrorism. Although the organisation has been weakened since 2002, al-Qaeda can still operate relatively unimpeded, especially in Yemen and has the strategic aspirations to carry out terrorist attacks at sea. As an example, Al-Qaeda in the Arabian Peninsula has declared that it wants to bring the Red Sea under “Islamic control” (Herbert-Burns, Countering piracy, STIMSON). Even though al-Qaeda is not able to truly control the Red Sea, these threats should not be ignored.

The idea that shipping is a target for Islamic fundamentalists is backed by the example of the attack of the terrorist organisation Abu Sayyaf on the ferry named SuperFerry 14 off the coast of the Philippines in 2004. The perpetrators smuggled a bomb on board disguised as a television set. The ship sunk and 63 bodies were recovered while another 53 were never found, making this the deadliest terrorist attack at sea to date. A more recent example of terrorism at sea was committed by the Abdullah Azzam Brigades (AAB), a terrorist organisation linked to the Pakistani Taliban and al-Qaeda. In July 2010 the ABB committed an attack with a speedboat packed with explosives against the Japanese oil tanker M.Star, which was navigating the Strait of Hormuz. The resulting explosion wounded only one crew member and did not bring about any structural damage to the ship. The attack was nonetheless worrisome, as ABB or other terrorist organisations were not expected to have the capabilities to mount an attack from the sea against moving ships, at night, and in an area that is extensively patrolled.

It remains to be seen if terrorist organisations would or could use CBRN weapons at sea. Or in other words, if these organisations have the intent and the capacity to do so, assuming that they indeed can lay their hands on “ready-to-use” CBRN weapons or materials. Regarding the intent, the answer is that some groups probably would use these weapons if they could get hold of them. The Japanese sect Aum Shinrikyomade use of CBRN weapons for its attack with the nerve agent Sarin on the Tokyo subway in 1995. Al-Qaeda is also known to have an interest in acquiring CBRN weapons (R. Niblett ed., America and a Changed World (2010) 231).

Scenarios of maritime CBRN terrorism

When looking at the capacity of terrorist organisations to use CBRN weapons at sea the picture is less clear. In the literature on maritime terrorism one can find many scenarios that are considered possible, even probable. This includes “nightmare” scenarios such as the detonation of a nuclear device in a shipping container or bulk carrier in a port area. The impact of such a scenario would indeed be enormous; the Council on Foreign Relations estimates that even an imperfect one kiloton nuclear bomb in Manhattan could cause hundreds of thousands of casualties.

Transporting an average nuclear weapon in a standard forty foot container is theoretically perfectly possible. France, the Soviet Union and the U.S., as examples, all made nuclear warheads for artillery shells.

Moreover, new developments in missile systems such as the Russian “Club-K” system prove that it is even possible to fire a cruise-missile from a standard size container. Nonetheless, the scenario of a detonation of a nuclear device on a ship is seen by most experts as unlikely. To date, the chances that a terrorist organisation would be able to develop nuclear weapons on its own, are assessed as negligible. It is doubtful if countries with nuclear capabilities would knowingly supply terrorist groups with this technology and, security regulations in the nuclear area are strict. Even if a terrorist group could obtain a nuclear weapon (by stealing for example) using it in a container, or on a vessel in general, would pose great operational challenges.

Another popular scenario debated among experts which could have devastating consequences is that of the hijacking of a ship transporting volatile chemicals, to use it as a “floating bomb”against other ships or port infrastructures. The explosion of a ship transporting, for example, liquefied natural gas (LNG) in a densely populated port area or near a cruise ship could cause mass casualties and huge economic damage.

However, as in the “nuclear case”, this scenario is very difficult to carry out. To begin with, navigating a hijacked chemical tanker to its target would only be possible if the authorities in vicinity of the area did not receive a hijack alert, which seems unlikely. Secondly, igniting a chemical tanker is far from easy and would require a very high degree of technical competency.

A “dirty-bomb” in a shipping container

This leaves us with the question are there maritime CBRN terrorism scenarios that are more easily carried out? The answer is yes. An example of such a scenario is a Radiological Dispersal Device (RDD), also called a “dirty bomb”, in a container on a ship. Contrary to the earlier mentioned example of acquiring a nuclear weapon (or a biological or chemical weapon), obtaining radiological materials appears not to be particularly difficult. A RDD could consist of some radiological material from, for instance, a hospital which could be dispersed by a small amount of conventional explosives when detonated on a ship or during transport from the port. A 2005 survey showed for example that on average, nuclear experts thought that there existed a 40% chance that a dirty bomb would be used against the U.S. between 2005 and 2015. It has been argued that two small RDDs containing only five pounds of high explosives could contaminate an area of 5-10km.22 This would most likely not result in mass casualties, but the social, psychological, and economic consequences could be very substantial.

Moreover, smuggling something into a country using standard shipping containers appears relatively easy, as the experience with the smuggling of drugs and other illegal cargoes shows. Container shipping is rather anonymous, all containers look the same, and of all the containers that pass through ports around the world, currently only about two per cent are inspected  (Griffiths and Michael Jenks, ‘Maritime transport and destabilizing commodity flows’, SIPRI Policy Paper 32 (2012), 47). Additionally, containers are packed and transported by many different companies often far from a port. Throughout this extensive supply chain, no official inspection of the containers takes place on a routine basis. Fraud with cargo lists is also not uncommon and the locks and seals on a container form a far from “water tight” safety guarantee.

These factors in themselves however, do not make the deployment of a dirty-bomb in a port easy as such. The respective terrorist organisation would need to have specialist knowledge and protective equipment to work with radiological materials, which for instance could cause severe burns, or worse. To limit this risk the terrorist should know how to shield nuclear materials, both to protect himself and also to lessen the risk of detection. This would probably result in either a much larger device, making it difficult to transport, or in a much smaller and thus weaker source. These kinds of practical limitations may well deter many potentially interested terrorist organisations from using radiological, or any other type of CBRN weapon, at sea or in ports.

A conventional attack on a cargo ship or ferry

The probability of more conventional maritime terrorism seems to be greater, as these attacks are easier to conduct. An example of such a scenario is a terrorist attack on a cargo ship at sea, with for example small speedboats loaded with explosives. Such an attack is feasible, as the attacks directed against the Limburg and the M. Star demonstrated. Moreover, sinking a ship in a busy shipping lane like the Suez Canal or the Strait of Hormuz may be appealing to terrorists due to the likely huge media attention and serious economic consequences which would ensue. The reliance of today’s global economy on just-in-time deliveries implies that key sectors and businesses would be severely affected if disruptions in the supply chain persist for more than a few days.
This is not to say that this scenario is easy to carry out. While damaging a ship is rather easy, sinking a modern ship is far more difficult. Another important aspect of this scenario which might limit terrorist interest is that the number of possible casualties is far lower than in the earlier mentioned catastrophic scenarios. Merchant ships have relatively small crew numbers and creating an environmental disaster, which could happen when a ship carrying chemicals would sink, does not seem to be a prime goal for terrorists.

On the other hand, attacking a ferry might be an appealing option for terrorists who want to find a comparatively easy way to create mass casualties, as the earlier mentioned example of the bombing of the SuperFerry 14 in the Philippines showed. These ships carry many people, are a highly visible target and sail on a fixed time schedule along predefined routes, all factors which could make ferries an attractive target for terrorists.


Is the threat of maritime terrorism real? IB Consultancy believes it is, but alarmism makes no sense. Multiple terrorist groups have been active at sea and have shown their ability to damage large ocean-going ships. The attacks on the Limburg and the M. Star could indicate that terrorist organisations such as al-Qaeda are trying to enlarge their capacities to strike at sea. However, if one looks at the past, the risks of maritime terrorism seem much smaller. Sinking modern cargo ships appears to be challenging.
Moreover, many existing scenarios seem to be unlikely due to the enormous practical difficulties that must be overcome when executing them. This applies in particular to alarming scenarios such as a nuclear weapon in a container. Turning a chemical tanker into a “floating bomb” appears only slightly less difficult. Somewhat easier to execute would be the scenario involving a dirty-bomb in a shipping container, making this a serious threat; especially because an attack with an RDD does not have a large explosive effect in order to create enormous panic.