Strategic Environmental Assessment (SEA) is a procedure to assess environmental consequences of plans, programmes and policies. This report is based on a case study of planning for the Defence Review in 2004 and it describes how the SEA-approach can be used in the long-term planning. SEA can facilitate decisions in an environmentally sound direction, but SEA can also be a useful tool to allocate planning resources effectively. However, the environmental issues must be considered in early stages of decision-making processes in order to affect the final result. As for other strategic planning aspects, e.g. juridical or financial, the strategic environmental considerations should be on a central level. Consequently, organisational changes in the Armed Forces are probably needed to assure that environmental issues are dealt with on the same level, and within the same organisation, as other strategic issues.