Figure 1. The nested MAS inside each track agent

ABSTRACT

Maritime security is especially critical for countries like Singapore, an island nation situated on one of the world's busiest shipping routes, and whose economic prosperity is highly dependent on international trade at its busy port, trans-shipment container terminals, pertrochemical complexes and other hight-value units located along its coastline. Recent incidents have brought into focus the reality of asymmetric maritime terrorism and the vulnerabilities of ports, waterways and shipping routes.

This article is extracted from the author's recent thesis, inspired by similar work down in the area of air threat assessment. The thesis adopts the ideas and techniques suggested for identifying air threats and uses them in identifying asymmetric maritime threats in a milti-agent system (MAS) for the relatively less investigated but very important area of port and waterways security.

The thesis also features a mock Vessel Traffic System - Command and Control system to evaluate the MAS. Simulations of scenarios with hostilities in the port of Singapore and surrounding waterways test the ability of the models to identify the intent of multiple simulated surface contacts by blending data and information into integration networks. Expansion of the integration networks can yield the intent identification process of a surface contact used by the compound MAS. Face validation by domain experts generated very encouraging results.

Oliver Tan

BACKGROUND

The Port of Singapore is one of the busiest in the world. It is the focal point of approximately 200 shipping routes that connect Singapore to more than 600 ports in 120 countries, and there are about 1,000 ships in the port at any time (Lewis, 2002). A stone's throw away from the port is the Singapore Cruise Centre, the cruise hub of the Asia-Pacific for passenger liners as well as regional and domestic ferries1. Located on nearby offshore islands are oil terminals and refineries managed by many multi-national petroleum companies2. Each day, hundreds of vessels of all sizes, ranging from small dinghies and bum-boats to large cruise liners and oil tankers, traverse the deep but narrow band of sea surrounding the island3. The Maritime Port Authority of Singapore (MPA) is responsible for overseeing and monitoring the vessel movements in the sea-lanes, ensuring navigational safety in the port and managing the marine environment around the island4 .

The defence of Singapore Territorial Waters (STW) against potential sea threats lies in the hands of the Singapore Police Coast Guard (PCG) and the Republic of Singapore Navy (RSN). Both agencies work together to combat and deter sea robberies, piracy and hijacks5. Although well guarded by the PCG and RSN, the waters around STW remain vulnerable. The Straits of Malacca has received much attention for attacks against vessels at sea (Davis, 2004). However, in terms of relative risk, it is less dangerous than the zone east of Bintan Island. Bintan and neighbouring Batam Island, a free-trade zone that is just outside the STW, have long been recognised as venues where organised crime syndicates and pirate gangs meet, do business and plan major attacks (Davis, 2004). In these waters, ships are like "sitting ducks" as they tend to concentrate and slow as they approach the Straits of Singapore (Davis, 2004).

The types of maritime threats and the ways they can be executed are numerous and unpredictable. For example, terrorists on a perfectly legitimate cruise liner can scuttle it when it is approaching the cruise centre, potentially shutting down the waterways to the port. It is also possible for terrorists to hijack a vessel and ram it against the cruise centre, a container terminal or an oil refinery (Rohan, 2002). Deception and surprise are also tools used by maritime terrorists against naval ships. Even if a naval ship was fitted with long-range guns, a terrorist group can conduct a "wolf-pack" attack where a cluster of terrorist craft simultaneously overwhelms a target craft from multiple directions (Rohan, 2002).

EFFORTS TO ENHANCE INTERNATIONAL MARITIME SECURITY

In November 2001, the International Maritime Organisation (IMO) Assembly adopted a resolution to develop appropriate measures to enhance maritime security in order to preclude a terrorist attack from the sea. In December 2002, the IMO adopted new maritime security measures that included amendments to the 1974 Convention of Safety of Life at Sea (SOLAS 74) as well as a new mandatory International Ships and Port Facilities Security (ISPS) Code (Englebert, 2003). Some of the amendments that have already been adopted or extended by the MPA include:

- The installation of shipboard Automatic Identification Systems (AIS) (Maritime and Port Authority of Singapore, 2003a; International Maritime Organisation, 2001)

- The equipment of silent ship-to-shore security alert systems (Maritime and Port Authority of Singapore, 2004a)

- The request for information related to ship security that a ship may be required to provide prior to entering the port as well as an initial inspection of the ship when in the port (Maritime and Port Authority of Singapore, 2003b)

- The need for vessels to maintain a continuous record of registration, ownership and other information that can be used by port control officers to assess for any security risk (Maritime and Port Authority of Singapore, 2004b)

- The extension of the ISPS Code to include mandatory compliance by small vessels and harbour craft that operate solely within the port limits (Maritime and Port Authority of Singapore, 2004c)

A MULTI-AGENT SYSTEM FOR SURFACE CONTACT INTENT TRACKING

The three main agencies that provide surveillance of the waters around Singapore are the MPA, PCG and RSN. As they focused on different areas and regions, it is therefore possible for each agency to develop different surveillance blind spots. A composite surveillance picture may help to mitigate the effects of the surveillance blind spots for each agency. Many information and intelligence sources contribute to a composite surveillance picture. Some important information sources include the Port Traffic Management System (PTMS) and the Vessel Traffic Information System (VTIS) that are used to manage vessel traffic in harbours and waterways6.

However, with a monthly record of almost 11,000 vessel arrivals into the Port of Singapore3, and many more unrecorded smaller leisure and fishing vessels, the number of surface contacts presented on a common composite surveillance picture is still overwhelming. It would be very difficult for port control officers to identify surface contacts with mischievous or potentially hostile intention before they strike. Furthermore, knowing the identity of surface contacts is insufficient for discovering potential incoming threats to civilian or military craft.
The idea of using a multiagent system (MAS) for the identification of potentially hostile behaviour and potential threats in ports and waterways is inspired by Ozkan's work in an autonomous agent-based simulation system for air-threat assessment (Ozkan, 2004). The simulation system incorporated the idea of conceptual blending (Giles and Turner, 2002) together with the research by Amori on a multi-agent system for adversarial plan recognition (Amori, 1992) and Liebhaber's study on airborne threat assessment (Liebhaber and Smith, 1999), to build a model that is capable of predicting the intent of air tracks. Besides predicting track intent, the system was also able to identify co-ordinated activities between air tracks.

Together with ideas from Liebhaber's preliminary research in surface warfare threat assessment (Liebhaber and Feher, 2002), a MAS for threat assessment can be applied in the domain of surface contact intent tracking. The MAS can sieve through hundreds of surface contacts in a composite surveillance picture and highlight any suspicious or potentially hostile tracks. The MAS integrates rules, track attributes and threat assessment cues into intent models. It also uses information provided under the new amendments to the SOLAS convention (Engelbert, 2003). These include the shipboard AIS, registries of vessel registration, vessel ownership, cargo manifests, and vessel transit schedules. All surface contacts that are within the port and STW are also monitored by the MAS for suspicious behaviour. Such behaviour may include loitering, violations of international navigation rules, encroachment into restricted areas, aggressive manoeuvres and even unusual co-ordinated activities among surface contacts.