The Japanese were far weaker in 1939 than in 1941. The IJNAS benefited greatly from the rapid changes in aircraft design and technology that swept the industry in the early war years, with the A6M reaching service at exactly the right time to be a significant force (the IJAAS benefited, although not as significantly, from the introduction of the Ki-43 in the same time frame).
In 1939 the Japanese are just introducing the Ki-27 and A5M, neither of which is qualitatively superior to the Allied aircraft they would face, and the other Japanese fighter, the A4N and Ki-10 are markedly inferior to the newest Western designs (a Spitfire, Hurricane, or Curtiss Hawk would chop any of these Japanese designs to pieces, and even the Gauntlet and Gladiator were more than a match for the A4N and Ki-10).
The Japanese were never that much of a match on the ground for the Western Armies in a set piece, even fight. They benefited greatly from managing a surprise assault against mainly colonial forces that were ill prepared and trained that was conducted by Japanese troops who were combat veterans. This massive advantage (there is simply no replacement for actual battle experience in preparing troops) does not exist in this scenario since the IJA has not been engaged in what was by 1941 better than five years of constant combat.
There is also the not inconsiderable matter of operational distance. The Japanese had bases in French Indochina to stage their attacks against Malaya and the DEI, as well as significant forces in China and on Hanan to act as logistical bases to support the move into the Southern Resource Area. In this scenario the closest Japanese support base is in the Palaus or the Mandates, with most forces having to come from Formosa or the Home Islands. The Japanese were NOT well equipped to operate at long range from logistical support.
Any IJN movement toward the Southern Resource Area would also undoubted be observed by U.S. forces operating out of the PI and Guam. While it is extremely unlikely that the U.S. would engage the Japanese, it is also close it ASB to imagine that the Americans wouldn't pick up the phone and call the British Embassy to have a quiet chat.
Overall the Japanese would be in a gravely disadvantageous situation, operating far from home, with long, extremely vulnerable supply lines, against well supplied and equally well prepared European forces that would not be surprised and would not be at the short end of the technological teeter-totter.
Lastly (and perhaps most critically) there would be absolutely no reason for the Japanese to attack the Europeans in this scenario. If they are not engaged in China, or occupying French Indochina the United States has not frozen their dollar assets, cut off oil and metal imports, or done anything else that forced the Japanese into their desperate lunge south. Without the war in China the IJA and IJN are also not in any burning need for supplies.
Simply put, without the war against China, the Japanese have utterly no reason to engage in any aggression of any kind.
In 1939 the Japanese are just introducing the Ki-27 and A5M, neither of which is qualitatively superior to the Allied aircraft they would face, and the other Japanese fighter, the A4N and Ki-10 are markedly inferior to the newest Western designs (a Spitfire, Hurricane, or Curtiss Hawk would chop any of these Japanese designs to pieces, and even the Gauntlet and Gladiator were more than a match for the A4N and Ki-10).
The Japanese were never that much of a match on the ground for the Western Armies in a set piece, even fight. They benefited greatly from managing a surprise assault against mainly colonial forces that were ill prepared and trained that was conducted by Japanese troops who were combat veterans. This massive advantage (there is simply no replacement for actual battle experience in preparing troops) does not exist in this scenario since the IJA has not been engaged in what was by 1941 better than five years of constant combat.
There is also the not inconsiderable matter of operational distance. The Japanese had bases in French Indochina to stage their attacks against Malaya and the DEI, as well as significant forces in China and on Hanan to act as logistical bases to support the move into the Southern Resource Area. In this scenario the closest Japanese support base is in the Palaus or the Mandates, with most forces having to come from Formosa or the Home Islands. The Japanese were NOT well equipped to operate at long range from logistical support.
Any IJN movement toward the Southern Resource Area would also undoubted be observed by U.S. forces operating out of the PI and Guam. While it is extremely unlikely that the U.S. would engage the Japanese, it is also close it ASB to imagine that the Americans wouldn't pick up the phone and call the British Embassy to have a quiet chat.
Overall the Japanese would be in a gravely disadvantageous situation, operating far from home, with long, extremely vulnerable supply lines, against well supplied and equally well prepared European forces that would not be surprised and would not be at the short end of the technological teeter-totter.
Lastly (and perhaps most critically) there would be absolutely no reason for the Japanese to attack the Europeans in this scenario. If they are not engaged in China, or occupying French Indochina the United States has not frozen their dollar assets, cut off oil and metal imports, or done anything else that forced the Japanese into their desperate lunge south. Without the war in China the IJA and IJN are also not in any burning need for supplies.
Simply put, without the war against China, the Japanese have utterly no reason to engage in any aggression of any kind.
