In spring 1942 the Japanese naval high command confronted a strategic dilemma. Ironically, the difficulty stemmed from the spectacular success Japanese arms had enjoyed in the war to date. The aim in December 1941 had been, first, to occupy Southeast Asia and the East Indies and, second, to establish an island perimeter shielding this “Southern Resources Area and the Home Islands from the inevitable U.S. counteroffensive. The Japanese had accomplished these conquests in approximately half the time anticipated. For practical purposes, the Imperial Navy had run out of plans.
For further reading: John B. Lundstrom, The First South Pacific Campaign (Annapolis, MD: Naval Institute Press, 1976); Bernard A. Millon. trans. S. V. Whitley, The Battle of the Coral Sea (Annapolis, MD: Naval Institute Press, 1974); H. P. Willmott, The Barrier and the Javelin (Annapolis, MD: Naval Institute Press, 1983).