Political map of East Asia and the Western Pacific 08 May 1942 (Battle of the Coral Sea): After  conquering Southeast Asia (Dutch East Indies campaign), Japan moved to cut Australia's supply line to the US by completing the occupation of New Guinea and its neighboring islands (Operation Mo). However, the Japanese invasion fleet had to be turned back when it ran into an American carrier force in the Coral Sea. The ensuing battle (Battle of the Coral Sea) was dominated by aircraft carriers, with neither side's ships sighting each other.