While nervous nations tighten their air and land security against the threat of terrorism, the world's waterways are suffering record levels of pirate attacks. The most dangerous of these maritime bandits have traded cutlasses for rocket-propelled grenade launchers, and wooden sloops for fleets of stealthy speedboats.
Last year 445 pirate attacks were reported worldwide, and for every successful raid many are thwarted and even more go unreported. Most worryingly for Australia, piracy has radically intensified in the Straits of Malacca, the narrow body of water between Malaysia and Sumatra, which now hosts more than half of global piracy. The world's most dangerous waters are uncomfortably close to home.
In the first two weeks of November, 11 seaborne attacks were recorded in South-East Asia, including the attempted ramming by two boats of an Australian naval vessel off the Northern Territory, and the boarding and robbing of an LPG (Liquefied Petroleum Gas) tanker in Indonesian waters.
These incidents highlight the emergence of increasingly sophisticated, audacious and violent pirate gangs, and the vulnerability of ships, including naval vessels and those carrying volatile cargo.
Australia's sea-lanes are at risk. The infiltration of organised crime into piracy has made these incursions more dangerous, more ambitious and harder to stop. But the problem gets worse.
New evidence shows global jihadists are entering the fray. Indeed regional terrorists and insurgents in South-East Asia have a history of using the sea as a launching pad for brutal acts.
The Abu Sayyaf group, a small, breakaway faction of Muslim Filipino separatists, has twice kidnapped tourists from island resorts using speedboats, and this year it claimed responsibility for an explosion on a ferry in the southern Philippines that killed 100 people.
The Moro Islamic Liberation Front has sea capabilities and, along with Abu Sayyaf, known links to al-Qaeda. Rebels in the Indonesian province of Aceh are hijacking ships and holding crews to ransom, while the Moro front and Sri Lanka's Tamil Tigers have even tried to acquire mini submarines.
International terrorists are now operating in pirate areas, adopting the techniques of pirates or franchising their cause to local insurgent groups. Centres of Islamic militant activity - Sudan, Somalia, Saudi Arabia, Yemen, Iran, India, Bangladesh, Indonesia, Malaysia, the Philippines - all have significant piracy problems off their coasts.
The term "pirate" therefore, masks a critical difference between more traditional banditry - even sophisticated versions with links to organised crime - and sea-faring terrorism. The latter is ideologically motivated and prepared to take far greater risks to further its cause.
While organised pirates disrupt trade and may inflict casualties during their operations, sea-terrorists make that disruption the primary aim - not just the by-product - of their attacks. If the ocean remains vulnerable, it may become the next battleground for the asymmetrical warfare of global jihadists.
South-East Asia has three vulnerable "choke points" - the Straits of Malacca, Sunda (between Java and Sumatra) and Lombok (east of Bali) - which are used by half the world's shipping. As financial and security controls on land grip harder, terrorists are using the sea to smuggle drugs and counterfeit goods to fund their operations. Coastal towns - including 80 per cent of the world's capital cities - are extremely vulnerable to terrorist groups with seafaring capabilities: they can pack ships with explosives, including "dirty bombs", smuggle in terrorists and weapons, and fire missiles from boats into chemical tankers.