The Imperial Defence Policy assigns the navy the task of forestalling and destroying enemy sea power, while the army is to seize the initiative by concentrating first in the chosen area. Those roles leave room for disagreement between the services over where effort should fall. Southern Expansion Doctrine, or Nanshin-ron, points toward operations in Southeast Asia and the western Pacific, especially if aggressive leaders such as Prince Fushimi Hiroyasu and Osami Nagano prevail. Mitsumasa Yonai's influence could moderate that commitment and favor an interception-attrition strategy closer to Japan instead. Leadership therefore shapes the choice between the Philippines and Singapore as much as geography does.
Notable Point · 33:16-37:27
Imperial Defence Policy divides naval and army roles
Japan's Imperial Defence Policy assigns the navy and army different opening tasks, while Nanshin-ron pushes strategy toward southern expansion.