This is merely a discussion, no timeline (yet) Long Post Assumption number 1. Japan does not enter war with China. Assumption number 2. A paradigm shift in the Japanese supreme HQ occurs and staffers realise that the Philippines is no threat to Japanese SLOC as long as the USA is neutral or friendly. Japan enters the war on Germanys side in late -39 (November/December) against France and Great Britain. What would the consequences be? How would the USA respond if Japan claim this only to be a colonial war? (remember no war with China) Allied Strongpoints: (dates are for the information available OTL) Hong Kong (September 1st 1939) Hong Kong Brigade - Two battalions of Infantry, one MG battalion Hong Kong Volunteer Defence Corps - Seven companies (roughly two battalions) of HKVDC 5th Cruiser Squadron CA.54 HMS Kent CA.56 HMS Cornwall CA.40 HMS Dorsetshire CL.19 HMS Birmingham CV.94 HMS Eagle 21st Destroyer Flotilla DDH.75 HMS Decoy DDH.07 HMS Defender DDH.38 HMS Delight DDH.64 HMS Duchess DDH.53 HMS Dainty DDH.16 HMS Daring DDH.49 HMS Diana DDH.22 HMS Diamond DDH.51 HMS Scout DDH.04 HMS Tenedos DDH.86 HMS Thracian DDH.29 HMS Thanet DDH.50 HMS Stronghold 9 Minesweepers 15 submarines Various patrol boats and other smaller crafts French Indo-China (May 10th 1940) Divison du Tonkin - One colonial infantry regiment, one mixed colonial infantry regiment, one Foreign Legion regiment, three Tonkineese tirailleurs regiments, one colonial artillery regiment Divison de Cochinchine-Cambodge - One colonial infantry regiment, two Annamese tirailleurs regiments, one Cambodian tirailleurs regiment, one colonial artillery regiment Bridgade d'Annam-Laos - One colonial infantry regiment, one mixed colonial infantry regiment, one South Anam Montagnard tirailleurs battalion. Groupe Aérien Autonme 41 - 9x Potez 25, 4x Farman 221 Groupe Aérien Autonme 42 - 10x Potez, 6x Potez 542 Groupe Aérien Mixte 595 - 7x Potez 25 Groupe Aérien Mixte 596 - 6x Potez 6 Esc. 1/C.B.S. - 8x Loire 130, 4x CAMS 37 & 55 5th Cruiser Division CL Lamotte-Picquett CA Suffren 1 Submarine Small number of gunboats Malaya (September 1st 1939) Federal Malay States Volunteer Force - Four battalions of FMSVF Penang Fortress - One Punjab battalion, one SSVF battalion, one artillery battalion Three Independent battalions (one Malay, one SSVF one Johore Volunteer Force) Singapore (September 1st 1939) 12th Indian Brigade - 3 Infantry battalions, one artillery battalion Malay Brigade - 2 Infantry battalions, one MG Battalion Straits Settlements Volunteer Force - two battalions of SSVF No. 11, 34, 39, 62 Squadrons with unknown number of Blenheim I No. 100 and 36 Squadron with unknown number of Vildebeest III No. 205 Squadron with six (6) Singapore III No. 230 Squadron with unknown number of Sunderland I Question: How much of these forces (particularly naval forces) had been withdrawn to Europe in the first two months of the war? Japanese Forces Nihon Kaigun (late 1939) IJN Kaga IJN Akagi IJN Soryu IJN Hiryu INJ Ryujo IJN Kongo IJN Hiei (under reconstruction, finished January 31st 1940) IJN Kirishima IJN Haruna IJN Fuso (under modernisation finished September 15th 1941?!) IJN Yamashiro IJN Ise IJN Hyuga IJN Nagato IJN Mutsu IJN Furutaka IJN Kao IJN Aoba IJN Kinugasa IJN Myoko IJN Nachi IJN Haguro IJN Ashigara IJN Takao IJN Atago IJN Maya IJN Chokai IJN Mogami IJN Mikuma IJN Suzuya IJN Kumano IJN Tone IJN Chikuma IJN Tenryu IJN Tatsuta IJN Kuma IJN Tama IJN Kitakami IJN Oi IJN Kiso IJN Nagara IJN Isuzu IJN Yura IJN Natori IJN Kinu IJN Abukama IJN Naka IJN Sendai IJN Jintsu IJN Yubari 11 Mutsuki-class destroyers 20 Fubuki-class destroyers 4 Akatsuki-class destroyers 6 Hatsuharu-class destroyers 10 Shiratsuyu-class destroyers 10 Asashio-class destroyers (a few still being completed in late -39) 44 Submarines Numerous smaller vessels Naval Aviation A5M mainly in use A6M production began in March 1939 B5N1 production began in 1938 (B5N2 production began in 1939) D3A1 production began in December 1939 G3M1 production began in 1936 Imperial Army (December 7th 1941) 44 Triangular Infantry division 8 Square Infantry divisions 22 Independent mixed brigades 3 Independent mixed regiments 10 Mongolian Cavalry Divisions 3 Armoured Brigades 1 Armoured Regiment 1 Cavalry Brigades 1 Paratrooper Division Army Aviation Ki-27 Mainstay fighter (unknown number) Ki-30 production began in 1938 Ki-32 production began in 1938 Unfortunately I have not been able to find any sources regarding the Imperial Japanese Army in summer/autumn 1939. Logically it would be smaller, but how much? Particularly if we factor in the assumptions at the start. That of no war with China. How much smaller would be reasonable? How would this turn out? My hypothesis is that the Japanese would attack in two stages. The first stage is a strike first at Hong Kong and Indo-China with naval landings at Haiphong, Hue and Saigon in Indo-China. But how would Hong Kong be taken? Direct landing at Hong Kong Island or at the mainland? The second stage would be conducted after Hong Kong have been neutralised and Indo-China occupied. Basing out of Saigon and Camh-Ranh-bay, covered by aircraft, the Japanese would land close to where they did historically and then march down the Malay peninsula towards Singapore. Allied Response: What would the French the British response be? How much forces can they divert from Europe? I can see naval forces being reasonable, particularly from the Royal Navy, as the French are able to tie up the Italians should they get involved. But how strong naval forces dare Royal Navy send to the East Indies? Two battleships? Three? A battlecruiser? A precious aircraft carrier after having lost both HMS Glorious and HMS Courageous? Ground forces then? I bet the Australians and New Zealanders will not go to North Africa. Indians troops sent to Burma and maybe Malaya instead of North Africa? In what numbers? Air forces? I think none can be spared. Britain and France were both strapped for aircraft as it was. Thoughts?