A strong interplay exists between the law of the sea and security at both the national and regional levels. The law of the sea provides the legal framework for national rights and obligations at sea, while it is also an important catalyst for regional security cooperation and dialogue. A stable maritime regime, underpinned by agreement on fundamental principles of the law of the sea, is an important contribution to regional security. However, the law of the sea can also be a potential source of tension. In the past, it was largely the preserve of major Western maritime powers, but in the last 30 years or so, it has had to change significantly to meet the needs of newly emergent nations, including some in East Asia, particularly Indonesia, that have been very active in defining the contemporary law of the sea.