Abstract   There are myriad threats to maritime security, including hijacking, murder, narcotics trafficking, migrant smuggling, support for terrorist organizations and transport of dangerous weapons. To enhance maritime security, the principles of co-operation and flag state jurisdiction provide the legal foundation for ship boarding and enforcement. Such co-operation should include boarding states promptly seeking, and flag states promptly confirming, claims of nationality, and, where reasonable indications of illicit activity exist, authorizing boarding and search, or doing so themselves. Proposed amendments to the SUA Convention will clarify the Convention's role in combating violence at sea, require States to criminalize such behavior, and establish uniform standards for responding to maritime terrorism.