In his magisterial history of Japanese-American diplomatic relations, Walter LaFeber offers up a compact history of World War II, with an unfailing eye for telling detail;
Although Japanese forces were already badly overstretched, Tokyo officials nevertheless held thirteen to fifteen divisions in Manchuria just to keep an eye on the Soviet Union and, mostly, sit on their hands. This error in decision making, together with the twenty-five and more divisions tied down in the bottomless morass of the China war, ruined Japan's ability to confront ever-increasing U.S. and British forces. In September 1943, the Emperor approved a decision to forget about thhe Co-Prosperity Sphere and to pull back to the main defensive line. In stark contrast to such belt-tightening, the United States built a ship whose sole task was to produce 5,100 gallons of ice cream per hour for Americans in the South Pacific.
--Walter LaFeber, The Clash 224 (1997)