Australia's regional security environment is characterised by rapid change, increasing complexity of security concerns, and great uncertainty. An increasing number of actors from further afield - more particularly Japan, China and India - are acquiring significant power projection capabilities. Many of the states within the region are themselves engaging in significant defence buildups. Security concerns are broadening to include economic and environmental issues. This rapidly changing, increasingly complex and more uncertain regional security environment can best be managed through the institution of various forms of enhanced security cooperation. The most fruitful approach is the establishment of 'building blocks' - a multiplicity of subregional arrangements dealing with various security issues and involving various memberships, building on the wide range of bilateral and limited multilateral arrangements already in place and addressing the common security concerns already being identified in the region. This monograph provides a detailed critique of a dozen 'building blocks' for regional security. Many of these involve the qualitative enhancement of existing arrangements and practices, such as strengthening and expanding current bilateral mechanisms for cooperation with respect to defence and intelligence activities, or building upon extant institutions such as the ASEAN Post Ministerial Conferences (PMCs) to provide a forum for regional dialogue and conflict resolution. Others include a regional maritime surveillance and safety regime, a regional avoidance of incidents at sea regime, a regional airspace surveillance and control regime, and regional regimes for monitoring the introduction of new technology into the region and for addressing issues of environmental security in the region. The focus of the discussion of these various confidence and security building measures (CSBMs) is on the practical and operational considerations involved in their implementation and subsequent operation. An appreciation of these considerations provides a realistic basis upon which viable and meaningful building blocks for regional security can be constructed.