Southeast Asian security is shaped both by its external Asian environment and by dynamics within Southeast Asia. This essay deals briefly with each dimension in turn.

The region's external security environment is becoming more complex with the rise of new powers like China and India, a more assertive Russia, and their geo-political aspirations and military modernizations. Hence, even with the increasing economic inter-dependence and the cooperative security endeavours in the various ASEAN (Association of Southeast Asian Nations) related forums, there is a degree of underlying fluidity and uncertainty about the longer term alignments of the major powers and their attitude towards Southeast Asia.

However, looking ahead just the next few years, the positive trends of the recent past can be expected to continue. First, the U.S. military presence and certain key alliances that underpin East/Southeast Asian security will remain in place. The strengthening of America's alliances with Japan and Australia in recent years and the growing trilateral cooperation among them suggest that the main maritime powers led by the United States will work more closely to balance a rising China, even as they, and others, engage and cooperate with China. Also noteworthy is the deepening strategic cooperation between India and the United States, but its future depends significantly on whether the U.S.-India nuclear deal gets through.

Second, bilateral relations between the United States and Japan on one side and China on the other can be expected to remain generally stable. China will be preoccupied with its internal development and the United States with the Middle East and Afghanistan, while being dependent on Chinese cooperation on a number of regional and international issues. The trend of improvement in Sino-Japanese relations set in motion by former Prime Minister Shinzo Abe is likely to be continued by Premier Fukuda. Sino-Indian relations have seen expanded dialogue and economic links but their future will depend in part upon how far U.S.-India strategic and defence cooperation advances.