Is there any way to have Japan go to war with the Allies and not bring in the USA? Is it possible that without a surprise attack, the US might not have gone to war? Would the US public have supported a war with Japan without Pearl Harbor?
Japan cannot attack the British and Dutch possessions in South East Asia in late 1941 and expect that the USA remains neutral.
Avoiding attacking American territory was suggested by at least two IJN admirals (In “The Japanese Navy in World War II”, ed. David C. Evans, page 6, Fukudome Shigeru stated that Adm. Shimada did not want to attack America. “The Origins of the Pacific War,” by Scott D. Sagan, Journal of Interdisciplinary History, Vol. 18, No. 4., Spring 1988, pp. 893-922 which attributes the idea of avoiding attack on American territory to Kondō Nobutake on page 913). However, this idea was rejected. The Army also wanted to go South only via Malaya but finally accepted the Navy's wish to invade the Philippines in September 1941 (for example in "Japan Prepares for Total War: The Search for Economic Security, 1919-1941" by Michael A. Barnhart on page 243 but referenced to Bōeichō, Daihon'ei rikugunbu 2, 416). However, there were still admirals who wanted to avoid the attack on Pearl Harbor because of its effect on American opinion. For example, Onishi Takijiro argued “...we should avoid anything like the Hawaiian operation that would put America's back up too badly” (“The Reluctant Admiral: Yamamoto and the Imperial Navy” by Agawa Hiroyuki, page 229).
The American position is discussed in “Going to war with Japan, 1937-1941” by Jonathan G. Utley and “To Have and Have Not: Southeast Asian Raw Materials and the Origins of the Pacific War” by Jonathan Marshall. Marshall page 162 notes that Roosevelt polled his cabinet members on whether they believed that “the American people would back up the administration if it chose to fight for the Western position in Asia” and all members agreed that they would (referenced to Simpson's Diary for 7th November 1941). We can see this in the contemporary Gallup polls where the answer to “Should the United States take steps now to prevent Japan from becoming more powerful, even if this means risking a war with Japan?” was “Yes (64%), No (25%) and No opinion (11%) in a poll taken from 10th to 29th October 1941. However, Hopkins recalled Roosevelt’s subsequent “relief” that the Japanese had attacked U.S. territory. “In spite of the disaster at Pearl Harbor and the blitzwarfare with the Japanese during the first few weeks, it completely solidified the American people and made the war upon Japan inevitable” (Sherwood, Roosevelt and Hopkins, pp.335-6). It also seems that Roosevelt planned to have an incident to sway American opinion and sent the small ships Isobel and Lanikai as bait (Marshall, page 170 and "The Strange Assignment of USS Lanikai" by Rear-Admiral Kemp Tolley, page 122-125 in "Air Raid, Pearl Harbor" by Paul Stillwell,
http://books.google.co.uk/books/abo..._USS_Lanikai.html?id=DTFbYgEACAAJ&redir_esc=y).
So naturally we turn to the question of whether Japan could have struck South in 1940 without provoking an immediate American response. This is a very difficult question. On the one hand, American leaders were conscious of the importance of the region for the American economy and Roosevelt was committed to helping Britain and may have warned Japan that America would oppose a move South as early as August 1940 (“The Origin of FDR's Promise to Support Britain Militarily in the Far East” by FW Marks,
http://www.jstor.org/pss/3639415). On the other hand, America was much more isolationist in 1940, which was an election year. The American Government began a programme of stockpiling raw materials such as rubber and tin from June 1940 and Marshall argues that there was a campaign to persuade the public of the importance of South East Asia from about the same time. There are some magazine articles from that period such as Time Magazine for 20th May 1940
http://www.time.com/time/magazine/article/0,9171,849271,00.html and
http://books.google.co.uk/books?id=...wBDgK#v=onepage&q=nitrile rubber 1941&f=false which certainly informed the American public and may also have persuaded them. There were no Gallup polls asking about war with Japan in 1940 but a Gallup poll taken from 16th to 21st February 1941 asked “Do you think the United States should risk war with Japan, if necessary, in order to keep Japan from taking the Dutch East Indies and Singapore?” and the replies were Yes (39%), No (46%) and No opinion (15%). Thus Roosevelt would have had to work much harder to bring America into a war in 1940 and early 1941 than later. He would almost certainly have tried to engineer an incident using small USN ships as discussed above but it is not clear if the IJN would have bitten on the bait.
Some relatively junior planners in the IJA did propose moving South in 1940 and Lieutenant-Colonel Nishiura Susumu, by an order of Colonel Iwakuro drafted a plan called “Guidance Plan for War in the South” (“The Japanese Road to Singapore: Japanese Perceptions of the Singapore Naval Base, 1921-41” by Yamamoto Fumihito, chapter 4
http://scholarbank.nus.edu.sg/bitstream/handle/10635/17361/07Yamamoto.pdf?sequence=7 and also Barnhart pages 158-9). Meanwhile the IJN concluded that an attack on the Dutch East Indies would involve war with America. I am not sure how that conclusion was reached. In "From Mahan to Pearl Harbor" by Sadao Asada (page 279), there is a brief mention of a war game on 26th-28th November 1940 presided over by Yamamoto with "leading members of the Naval General Staff". Marder's "Old Friends, New Enemies" attributes this to Rear-Adm. Maeda Minoru's view that the Dutch and Americans were the same race (interview on 19 June 1962 in Boeicho Senshibu Archives). However, it seems possible that the importance of American public opinion was not appreciated by the IJN. If there was interest in striking South at that time amongst the leaders of the IJA, they seem to have decided not to push the issue in the face of IJN opposition.
Finally, we might ask what would have happened had Japan struck South not one year early but two years early at the end of 1939. Naturally that was quite impossible because going to war on Germany's behalf was rather unpopular in Japan in 1939 after Germany had signed the Molotov – Ribbentrop Pact at the height of the Battle of Khalkhin Gol or Nomonhan.
However, we can suggest PODs to avoid the Khalkhin Gol or Nomonhan Incident. For example, there was a clash between Lieutenant-Generals Tada Hayao, Vice Chief of the General Staff, and Tojo Hideki, Vice Minister of War, in late 1938. Tada certainly believed that the USSR was Japan's main enemy. Tojo apparently believed that Japan should have been quicker to commit larger forces to China (Butow, Tojo and the coming of War, page 105). A more extreme opponent of reinforcement to China, Ishiwara Kanji, had already been sidelined after 1937. Might Tada's death or serious injury in an accident or by removal by illness have caused Tojo's (and perhaps Doihara's?) view to have been accepted that China had to take precedence over Manchuria. Was that Tojo's real view? His speech in November 1938 stated that Japan must arm for war against both China and the USSR. However, he seems to have regarded China as the more urgent issue (Butow, page 121).
It is still rather a stretch to imagine orders being given and obeyed that great restrain be shown to avoid border incidents against the Soviet Union (as were given OTL after September 1939) and that diplomatic efforts be made to improve relations with the USSR. However, had such policies been adopted to allow a focus on China, it seems possible that the combination of the Tientsin Incident
http://en.wikipedia.org/wiki/Tientsin_Incident and the outbreak of the war in Europe would have made an advance South in 1939 attractive.
It seems very likely that surprise Japanese landings in Malaya and Indochina in December 1939 would not have provoked an immediate American response, especially as American access to raw materials from the Netherlands East Indies would not have been threatened initially. As France and Britain were allies and Italy was neutral, it is possible that Japan would have faced more naval opposition than OTL two years later. However, a surprise attack might have succeeded. On May 10th 1940 (assuming no butterflies), we might assume that Japan, warned by Germany of its operations, would invade the NEI. However, America might be taken by surprise and not immediately react.
Now if we believe Marshall, American leaders decided in May-June 1940 OTL to prepare for war in defence of South East Asian raw materials. However, it might be much harder to argue for a war to regain those materials as, if they really were essential, would it not be easier simply to buy them from Japan? We might imagine that American politics have by now diverged from OTL. One less obvious reason is that there would probably not have been a German Invasion of Scandinavia because the British Fleet would have been sent East and Goering's OTL argument that the forces were needed for the campaign in the West would have triumphed. Thus American opinion might be a little more isolationist especially in the Mid West where voters of Scandinavian descent were concentrated. Thus it is just possible that we would have a Roosevelt – Taft or Roosevelt – Dewey election in 1940 fought upon the issue of whether to trade with Japan or to oppose Japan and suffer a severe recession due to a shortage of rubber and tin.