 Shortly after the war began, Japan's Naval General Staff recommended an invasion of Northern Australia to prevent Australia from being used as a base to threaten Japan's perimeter defences in the South Pacific.The Imperial Japanese Army (IJA) rejected the recommendation, stating that it did not have the forces or shipping capacity available to conduct such an operation.At the same time, Vice Admiral Shigeyoshi Inoue, commander of the IJN's Fourth Fleet (also called the South Seas Force) which consisted of most of the naval units in the South Pacific area, advocated the occupation of Tulagi in the southeastern Solomon Islands and Port Moresby in New Guinea, which would put Northern Australia within range of Japanese land-based aircraft.