Operation MO

Operation Mo
Map showing the movements of the Port Moresby invasion force, and the plan for the force's landing at Port Moresby
Planned	April 1942
Objective	Occupation of Port Moresby
Outcome	Abandoned following the Battle of the Coral Sea

Operation Mo (MO作戦, Mo Sakusen^?) or the Port Moresby Operation was a Japanese plan to take control of the Australian Territory of New Guinea during World War II as well as other locations in the South Pacific with the goal of isolating Australia and New Zealand from their ally the United States. The plan was developed by the Imperial Japanese Navy and supported by Admiral Isoroku Yamamoto, the commander-in-chief of the Combined Fleet. The operation ultimately failed.

When the Japanese Navy was planning the New Guinea Campaign (air strikes against Lae and Salamaua, disembarkation in Huon Gulf, New Britain (Rabaul), New Ireland (Kavieng), Finch Harbor (also called Finschhafen), and the capture of Morobe and Buna), strategists envisioned those territories as support points to implement the capture of Port Moresby. The implementation of these operations was assigned to the Japanese Naval task force led by Admiral Chūichi Nagumo, after completing the Java campaign. Another important step was the occupation of Christmas Island to the south of Java. The Japanese Navy General Staff had been considering Operation Mo since 1938, as a step in the consolidation of the Southern Seas areas in the Greater East Asia Co-Prosperity Sphere (大東亜共栄圏 Dai-tō-a Kyōeiken).