This article outlines the principles of international law governing the right to exercise jurisdiction over ships. It then explains the relevance of UN international crimes conventions to the security of commercial ships. These conventions give States parties jurisdiction to arrest persons present in their territory who are alleged to have committed such crimes and an obligation to either prosecute or extradite them. It then explains the measures that have been taken by the International Maritime Organization to enhance the security of commercial shipping, including its Code of Practice on preventing piracy and “armed robbery against ships” and its measures to address the threat of maritime terrorism against ships. It also discusses issues of jurisdiction over offenses classified as “armed robbery against ships.” The article then focuses on the measures that have been taken in Southeast Asia to enhance the security of commercial shipping, including measures taken by ASEAN and by neighboring States. It then discusses the 2002 Regional Cooperation Agreement on Combatting Piracy and Armed Robbery against Ships in Asia (“ReCAAP”) and the ReCAAP Information Sharing Centre (ISC), as well as the Information Fusion Centre (IFC) in Singapore. It argues the reporting of incidents by these organizations should be modified to take into account the rules of international law on jurisdiction over ships.