5. The situation clearly points to an enforced reduction in Japanese mobility from the Spring of 1943 onwards. This implies that the Japanese might have to change over to a strictly defensive policy, and endeavour to set up a defensive line held mainly by shore-based aircraft and naval forces operating under this cover, with which to inflict as much loss as possible on Allied attacking forces. The adoption of such a system would enable the Japanese to reduce the pool of shipping, held purely for military movements, to the level necessary for the quick movement of local reserves.