In the second half of the 20th century, international maritime transport experienced a prosperous period characterised by the growing integration of markets, by the globalisation of international trade flows and by great advances in technologies. This scenario has been dramatically disrupted by terrorist attacks with strong implications also in terms of policy. The importance of maritime transport security is determined by the high vulnerability of this mode of transport to terrorist attacks, given the extremely diversified routes and the enormous volume and wide range of shipped goods, whose origin, description and ownership are not always perfectly traceable. In addition, any interruption of the maritime transport chain due to international hostile actions may greatly affect the global economy. For all the above mentioned reasons, maritime security regulation has been moved to the top of the policy agenda. Throughout the world, international organisations, governments, customs and the private sector have shifted their efforts towards managing the newly required security issues, trying at the same time to safeguard operational effectiveness. However, the heterogeneous regulatory schemes that have been introduced, have sometimes overlapped or even contradicted each other. The aim of this paper is twofold. Firstly, it will analyse and discuss the United States (US) and the European Union (EU) approaches on maritime transport and port security, in a comparative way. The need for enhancing security standards has apparently generated heterogeneous policies. In this respect, the prompt response of the US to the increased terrorist threat has resulted in a series of initiatives oriented towards maximisation of internal security while the EU has adopted a strategy aiming at balancing security needs with other targets (e.g. privacy safeguard and trade defence). Lastly, the efforts made by international organisations towards the development of a coordinated maritime transport security regulation worldwide will be considered alongside the possibility of identifying a competent international organisation which could act as regulatory authority for maritime security at international level.