Would a Japanese Invasion of the USSR during Barbarossa have actually helped?

Thanks Bob. I know I've seen your analysis before and definitely didn't mean to make you dredge it all up again on demand. I wanted to reframe the discussion for all the people who thought there would be minimal effect on Soviet fighting in the west by looking at the fact that the east was still a net producer for them through the war. Your analysis makes that pretty clear. Beyond the acute loss in Lend-Lease while other routes are expanded the loss of hundreds of thousands of men, thousands of tanks and planes and tens of thousands of vehicles would surely be felt.

For the question of enticing Japan to attack, could the Germans basically promise them resources from the Soviet Union and equipment from Germany after the Soviet defeat? There was no shortage of optimism for either general staff. I could see an assessment that the two front war would force a Soviet surrender by 1942 with the transfer of oil, tanks and planes starting within months. I'm not saying this would be the outcome, but I could see both Germany and Japan believing it. As for whether Germany would be willing to give these concessions to Japan, with Stalin defeated they may still have to face the WAllies, but they should have some breathing room.
You're welcome, and don't worry, I enjoy sharing knowledge.

About the rest of your questions: even though the Soviet Far East produced some quantity of military equipment for that regime, it was not economically self-sufficient from European Russia. The Japanese army concluded that the relatively small population was disproportionately urban and consequently there weren't enough farmers in the region to grow food for everyone. Japanese calculations suggest that by 1945 yearly local production in Far Eastern Russia only covered 67% of bread-making grain, 66% of petroleum, and 38% of steel requirements. Hence, the balanced needed to be shipped from European Russia. Because the region's economy and the military forces stationed there both depended on the same Trans-Siberian railway, the more food, oil, and steel the Soviet regime shipped to the Far East, the less capacity would be available for military supplies in the event of war with Japan. Due to these limitations, Japanese planners estimated that the maximum size of any army force the Soviets could have fielded against them in the Far East at 55 to 60 divisions. (For comparison, the force the Soviets historically used in Manchuria in August 1945 - estimated by the Japanese at 1,600,000 men, 4,500 tanks, and 6,500 aircraft - was assessed as 47 divisions.) Further information can be found in JSOM vol. XIII (one of the 'special studies' prepared by the Japanese for the US Army after the war) where this subject is discussed in detail from page 17 onward.

In my opinion, the moment where the Japanese might have been convinced to collaborate with Germany in an invasion of the USSR was Matsuoka's visit to Berlin in March 1941. The Nazi foreign Minister Joachim von Ribbentrop deliberately concealed the details of operation Barbarossa from the Japanese and instead advocated for an attack on Singapore. Then the next month Matsuoka went to Moscow and concluded Japan's neutrality pact with the Soviets; after the Nazis and their European allies invaded the USSR in June Matsuoka then turned around and became one of the main advocates for tearing up the treaty he himself collaborated on and attacking the Soviets. Many Japanese army officers wanted the same, but the navy advocated only partial preparations (inadequate for an attack 'at a moment's notice') so that any buildup in Manchuria would not interfere with the other aggressive plans against Southeast Asia. The Japanese army itself was not unanimous on the extent of military preparations against the USSR, and the overall commander in China, Shunroku Hata, strenuously objected to the large redeployments of troops then under his command that the 'strike north' proponents wanted. General Itagaki, the incoming Korea Army commander, also opposed large-scale redeployments of troops (IIRC beyond 1-2 additional divisions) to Manchuria.

Even though the Japanese army was divided and the Japanese navy generally opposed attacking the USSR, the "strike north" faction, led by General Shinichi Tanaka, ended up getting their way when it came to the size of the military buildup in Manchuria - on the condition that no actual attack would take place without Hirohito's authorization. However, when the Germans started to bog down in Europe and the Soviets failed to transfer half their Far Eastern forces westward the Japanese army started to consider the Kantokuen plan to be less attractive. The final nail in the coffin came on 1 August 1941 when the United States cut off all oil exports to Japan, followed by the Netherlands East Indies shortly thereafter. After this, the Japanese military formally decided on 9 August to concentrate on plans for an attack against Southeast Asia and the buildup in Manchuria and Korea was limited to only 16 divisions.

In summary:

- Japan's regime felt the Molotov-Ribbentrop pact was a 'betrayal' of the anti-Comintern pact
- Japan's regime concluded their own neutrality pact with the USSR in April 1941
(^These two tended to divert the attention of the Japanese militarists to the south)​

- Germany attacked the USSR in June 1941; the Japanese regime felt "betrayed" again
- The Japanese militarists were divided between focusing on the south (preferred by the navy and some army elements) or building up for an attack on the USSR (preferred by some army elements. The Japanese army was arguably more in favor of attacking the USSR than going along with the navy's plans)
- The Japanese war ministry decided on a halfway measure: some additional forces would be sent to Manchuria, but not enough to undermine the navy's plan for aggression to the south.
- The buildup in Manchuria historically reached the level preferred by the war ministry, and measures were in place to increase the number further, but outside events prevented this (such as opposition from Hata and the US/NEI oil embargo).
- Thus, the Kantokuen plan was stopped before reaching the levels advocated by General Tanaka and others because the Japanese regime decided to concentrate on invading Southeast Asia first.

- The Japanese didn't completely abandon the idea of invading Siberia in 1942, but because of several factors this obviously never happened.
 
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The Japanese take everything south of the Amur, but are bogged down. If this in in addition to Pearl Harbor, the Philippines and DEI hold out for an extra month or two. The Battle of the Coral Sea is the massive naval disaster for Japan, not Midway. The Japanese might not even take Java or Sumatra. The Chinese do better since a couple divisions are moved to Russia. The Germans most likely take Moscow, but it is retaken during the Winter Offensive. The Battle of Stalingrad might last longer, and the Germans might reach the Caspian Sea. The Iran Supply Route would keep Soviet troops in Transcaucasia stocked up, preventing the Nazis from crossing the Caucasus Mountains. The Soviets still drive them back. The Battle of Kursk would drag out a little longer. The Soviet Progress in Europe would be a year behind OTL.

With more troops to spare, the Allies land in France a couple months earlier as well. There is a Balkan Campaign along with the Italian Campaig, with Yugoslavia cleared of enemy resistance in mid 1944. The Allies move into a collapsing Germany, with the Germans surrendering en masse to the WAllies, but fighting tooth and nail against the Red Army. The WAllies and Soviets link up Along the Bug River.

After the War in Europe ends, the WAllies have executed Operation Downfall, with the Soviets storming Amuria, Manchuria, and Korea. Japan gives up once Tokyo falls


tl;dr: Japan does worse and the Germans do better.
I don't see the relation between the Pacific theatre and a Japanese invasion of the Russian Far East. The forces in the the 2 theatres were not the same. Japan transferred a few divisions and mixed brigades from the Shanghai area specifically and a smattering of divisions from the rest of the Chinese front for the attacks on Malaya and Burma, in addition to forces in Japan and the SNLF troops under Naval Command for its early war assaults in the Pacific. Forces were not taken from Manchuria or Korea. Now, it is true that Japan is likely needing reserve division if it engages in combat in the Russian Far East, but I think its likely that they can take Vladivostok and get up to the Amur, as well as penetrate into Mongolia. I don't think that terrain allows for much else.

But I think it is possible that little changes in the Chinese front, as Japan was largely on the strategic defensive and focusing on consolidation and counter insurgency from the Winter Offensive up until Ichi-Go in China, with offensives being limited affairs. The Pacific was not manpower intensive for Japan until 1944 and the Marianas Campaign, and moreso on the invasion of the Phillipines by Macarthur.

As for the impact on the Soviets, it is likely that the Far Eastern troops cannot be used in the Moscow Counteroffensive, but the Transbaikal department troops could if the Japanese do not attempt offensives in the direction of Mongolia. I don't think we can rule out a German conquest of Moscow in the event that the counteroffensive doesn't go well, and the Germans make Moscow the focus in 1942. Remember, as oil crazy and Baku obsessed as Hitler was, it was ultimately input from his commanders about the futility of the Moscow front that convinced him on the need to look elsewhere - his commanders were hoping for a Northern offensive, I think, and he went the other way.

My personal view is that if the Germans cut the railway from Murmansk to Moscow, and the Japanese take Vladivostok, the Soviets are going to be stuck in the mud and the army is going to be mostly unmotorized unless they are able to take these routes back, and this will turn the East into a big stalemate, unless German offensives bear fruit. The Persian corridor is important but I don't think it was enough. Remember, the Soviets had massive food problems as well for most of the war and the possibility of divisions starving in the field was not as far off as you may think. These routes saw almost 75% of the American throughput and especially mattered in terms of food, metals, rolling stock, and vehicles.
 
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My personal view is that if the Germans cut the railway from Murmansk to Moscow, and the Japanese take Vladivostok, the Soviets are going to be stuck in the mud and the army is going to be mostly unmotorized unless they are able to take these routes back, and this will turn the East into a big stalemate, unless German offensives bear fruit. The Persian corridor is important but I don't think it was enough. Remember, the Soviets had massive food problems as well for most of the war and the possibility of divisions starving in the field was not as far off as you may think. These routes saw almost 75% of the American throughput and especially mattered in terms of food, metals, rolling stock, and vehicles.
No question that cutting the rail lines to the north and the east would have put the Soviet Union in a world of hurt. Dividing the very limited food rations between the troops and the defense workers would have been been a real challenge. Even a stalemate would have benefited the Germans. I could see some sort of truce.
 
I am not sure I agree with the premise. The Japanese Army high command was fixated on China but what if there were to view their position more objectively. They could have just accepted a stalemate and it is even possible Chiang Kai-shek would have accepted a truce. There certainly is no reason to suspect Chiang would have been any more active in response to a Japanese stand down or lessening of activity. There may have been a Soviet initiative for an attack against the Japanese in Burma. To me the decreased flow of Lend Lease supplies would be the most significant factor.
It is pretty unlikely that Chiang would be allowed to make a truce with the Japanese even if he at this point desired one. He had already been kidnapped in 1936 and told in no uncertain terms that if he wouldn't fight the Japanese, he would be replaced with someone who would. And that was before a whole lot of Japanese atrocities.

And the Chinese aren't stupid. If the Japanese start preparing for an assault into the Soviet Union there's going to be a slackening in China as resources are diverted away from those fronts (as there was in OTL), so if the Japanese try to negotiate a truce, people will smell rat.

In OTL, the Japanese pretty much did accept a stalemate in China to divert resources into the Pacific war. But that didn't end the war in China. Manpower and resources were still needed to hold back Chinese attacks. And until Japan is willing to at least withdraw back into Manchuria, I don't see any change in that. Which Japan isn't going to do because giving up the coastal regions of China at this point means accepting that they are a junior-grade empire.

I don't see the relation between the Pacific theatre and a Japanese invasion of the Russian Far East.
Oil for a start. Also, Japan has a pretty limited amount of steel for new weapons and machines. And didn't the Japanese assign some of their very best units to the Pacific war?

The Japanese already knew that they needed to get insanely lucky for everything to go right and to so psychologically over-awe the US that the Americans decide to agree to a quick peace. Invading the Soviet Union means two weaker attacks than they'd get if they focused on one at a time, and thus even lower chances of success.

fasquardon
 
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It is pretty unlikely that Chiang would be allowed to make a truce with the Japanese even if he at this point desired one. He had already been kidnapped in 1936 and told in no uncertain terms that if he wouldn't fight the Japanese, he would be replaced with someone who would. And that was before a whole lot of Japanese atrocities.
1936 was five long years before but a defacto truce rather than a formal agreement probably would have made more sense. I don't think Ching or Mao really cared what happened to the Chinese peasants. Sure they paid lip service to Atrocities, other than those they committed themselves.
 
1936 was five long years before but a defacto truce rather than a formal agreement probably would have made more sense. I don't think Ching or Mao really cared what happened to the Chinese peasants. Sure they paid lip service to Atrocities, other than those they committed themselves.
Japan had conquered the most urban and developed parts of China. Do you think the Rape of Nanking was inflicted on peasants? They don't need to care about the peasants to care about what Japan was doing. There were plenty of urban workers and middle and upper class Chinese being murdered, raped and abused as well as the many, many Chinese peasants who suffered at Japanese hands.

Also, what the heck is in it for the Chinese to accept a truce, either de factor or formally? The Japanese had already shown that they couldn't be trusted in negotiations in the 30s and not fighting Japan is going to lead to a reduction in foreign support and lessened chances of foreign intervention in China's favour. And perhaps more importantly, a truce would threaten the fragile truce between different Chinese factions, including different factions inside the KMT and CCP.

The Chinese are not just going to help the Japanese out because they're having a tough time in the war.

fasquardon
 
Oil for a start. Also, Japan has a pretty limited amount of steel for new weapons and machines. And didn't the Japanese assign some of their very best units to the Pacific war?

The Japanese already knew that they needed to get insanely lucky for everything to go right and to so psychologically over-awe the US that the Americans decide to agree to a quick peace. Invading the Soviet Union means two weaker attacks than they'd get if they focused on one at a time, and thus even lower chances of success.

fasquardon
The oil point is an issue, but the Japanese army in Manchuria was mostly unmotorized and the far bigger drain on oil came from the need to keep its naval operations going. They didn't use bicycles in Malaya and the Phillipines because of the terrain and bad roads; they did so because the divisions sent didn't have motor transport in China either. That said, assuming the East Indies operation goes well, oil supplies are going to be less of a problem (I know they had problems refining and transporting oil from there, but it'll be a little better)

The elite forces sent to the Pacific were the Marines of the SNLF, controlled by the Navy. They certainly did well in the engagements of 1942, but usually against pitiful defensive operations in the Solomons, Guam, and most of all the East Indies areas. The army, which was never keen on the Pacific war outside of the Burma/Malaya theatre, did not authorize top level forces to be taken even from Manchuria (at least until the death of Yamamoto, and afterwards, they did not send them in units but rather in individual replacements).

The army units sent to the Pacific were a mix of green divisions, veteran forces in the quiet Shanghai theatre, forces detached in Indochina or Taiwan, and existing defensive forces in the Japanese possessions in the Central Pacific. The navy was far better prepared than the army for war in the Pacific and it showed once the Allies put credible ground forces into the field. One thing to note: they did not often use the Independent Mixed Brigade unit in their orders of battle for the Pacific War, unlike in China where they were extremely common because of the nature of the fighting there. They would almost always consolidate forces into divisions instead once combat began. But these divisions could vary wildly in quality. By the time of Saipan, they were having serious problems fielding quality ground forces in the Pacific, partially because their forces were incredibly dispersed.

Japan had plenty of ground forces for a fight with the Soviets in the Far East. They would however have serious problems once casualties started mounting in terms of replacements and of material.
 
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Japan had conquered the most urban and developed parts of China. Do you think the Rape of Nanking was inflicted on peasants? They don't need to care about the peasants to care about what Japan was doing. There were plenty of urban workers and middle and upper class Chinese being murdered, raped and abused as well as the many, many Chinese peasants who suffered at Japanese hands
We obviously have very different opinions about Chiang. I don't think he or Mao cared about peasants, urban workers or anyone else. They were all about themselves. If a truce with Japan furthered Chiang's interest in advancing himself and his little cadre there is no doubt in my mind that is what he would have done. Same for Mao. Chiang basically sat back and waited for the Americans and British to defeat the Japanese. Had there been a Japanese Russian war in 1941 or 1942 Chiang would have done nothing different; he would have waited husbanding his forces for the coming war with Mao. Mao may have been incentivized to be more active to support the Soviets; which Chiang would have liked.
 
Chiang basically sat back and waited for the Americans and British to defeat the Japanese.
Oh wow you need to read more good histories of the Chinese front in WW2! Though to be fair, we have been rather cursed with a lack of those in English - for decades the best known source was Stilwell's utter pack of lies.

The Chinese fought energetically and with determination. Which is amazing when you consider just how bad their supply situation was and how bad their "allies" were screwing them. Especially Stilwell, who in my book was the worst commander of the whole war. The Japanese had no greater friend in the US. (Though Stilwell would have been a great camp commander if he'd stayed on the home front training men, he had no ability to deal with theater level command and wouldn't take responsibility for his own screw-ups, which I consider an especially odious personal failing. Though Chiang did have some part in the Stilwell's screw ups - instead of treating Stilwell like a professional general and sending him home in disgrace, Chiang dealt with him like a warlord who had to be placated.)

The oil point is an issue, but the Japanese army in Manchuria was mostly unmotorized and the far bigger drain on oil came from the need to keep its naval operations going. They didn't use bicycles in Malaya and the Phillipines because of the terrain and bad roads; they did so because the divisions sent didn't have motor transport in China either. That said, assuming the East Indies operation goes well, oil supplies are going to be less of a problem (I know they had problems refining and transporting oil from there, but it'll be a little better)
If memory serves, the Japanese weren't able to get any significant oil production from the DEI. Or at least, not before their logistics were so badly interdicted that it didn't matter.

And again, you are assuming that the Japanese can go North and South both at once. Or that they'll want to.

You are right of course that ships consume more oil products than anything else in the period, but a push into the Soviet Union is going to need oil still, and alot of it because even a Japanese army uses a whole lot of oil and lubricants when on the move. The US oil embargo really hurt Japanese operations in China, and an invasion of the USSR would need to be even more mechanized per man involved than the fighting against China. And unlike going South, there's really no chance the Japanese can get more oil.

fasquardon
 
If memory serves, the Japanese weren't able to get any significant oil production from the DEI. Or at least, not before their logistics were so badly interdicted that it didn't matter.

And again, you are assuming that the Japanese can go North and South both at once. Or that they'll want to.

You are right of course that ships consume more oil products than anything else in the period, but a push into the Soviet Union is going to need oil still, and alot of it because even a Japanese army uses a whole lot of oil and lubricants when on the move. The US oil embargo really hurt Japanese operations in China, and an invasion of the USSR would need to be even more mechanized per man involved than the fighting against China. And unlike going South, there's really no chance the Japanese can get more oil.

fasquardon
It was basically hopeless by late 1943 as American submarines sat on the transport route. So for the oil to matter much after that point you'd need some pretty big PODs. Part of the biggest problem was that they had real issues refining the oil in Borneo or wherever the facilities were in DEI first, and had to ship it to the Home Islands, thereby increasing tanker usage and stretching escort capacity. That, and the fact that Japan had a real shortage of petroleum engineers and one of the biggest shipments of these people to DEI was sank by a submarine in early 1942.

But Japan's oil reserves in 1942 and early 1943 did see real rises that could matter in this scenario.

As for combat in the Far East, the terrain is pretty awful for any kind of logistics, something that benefits Japanese Divisions and would make combat far more dependent on infiltration style short attacks, again, something that would benefit the Japanese. Especially if we consider that its unlikely the Japanese are able to make many advances past the Amur River or deep into Mongolia, I think its fair to assume that they'd be perfect capable of carrying out a limited offensive that achieves these goals. Being the Japanese army, they'd likely try to continue it past that and fail. But would this have an impact on Barbarossa? I think it would. As long as they take Vladivostok and cut the railway from the Pacific Coast to Moscow, it matters very much.

The Soviet units in the Far East and Trans Baikal, for what its worth, had only a single Mechanized Division and a fair number of cavalry formations in forces that became the TransBaikal front. Some of its forces were completely immobile, being stationed in the Fortified Region commands (the Germans tended to surround and destroy these very easily; I'd imagine they'd be more important in the Far East, but not that much, as many had essentially the cast-offs in manpower), and they had no real dedicated armored formations. I am just not convinced that the fuel usage would be substantially more there than in China. They'd run into real problems because of poor logistics, but if they take Vladivostok fairly early in the fighting, with port facilities intact, these problems become a lot less serious.

My overall contention is that the Japanese accomplished its major successes in 1941-1942 in the Pacific on kind of a shoestring budget from an army perspective. The bulk of Japanese forces were in China and Manchuria at the time, and the removal of forces for the Pacific War were not yet all that serious and would not be in a way that affected what fighting looked like in Manchuria until at least mid to late 1943 when they started stripping the Kwantung Army of individual manpower for new formations in the Pacific. This does not mean that the Japanese would even win a long term campaign in the Russian Far East, I think eventually they'd lose, but early in the war, I'm not positive of this.
 
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Oh wow you need to read more good histories of the Chinese front in WW2! Though to be fair, we have been rather cursed with a lack of those in English - for decades the best known source was Stilwell's utter pack of lies.

The Chinese fought energetically and with determination. Which is amazing when you consider just how bad their supply situation was and how bad their "allies" were screwing them. Especially Stilwell, who in my book was the worst commander of the whole war. The Japanese had no greater friend in the US. (Though Stilwell would have been a great camp commander if he'd stayed on the home front training men, he had no ability to deal with theater level command and wouldn't take responsibility for his own screw-ups, which I consider an especially odious personal failing. Though Chiang did have some part in the Stilwell's screw ups - instead of treating Stilwell like a professional general and sending him home in disgrace, Chiang dealt with him like a warlord who had to be placated
I admit I am not a student of the China theater. I also admit that Stilwell benefited from two well written and hugely popular biographies by Theodore White and Barbara Tuchman. None the less what I have read has led me to form a very low opinion of Chiang Kai-shek. Basically I see him as an opportunist ruling by terror and starving his people for his life as a potentate.
 
You're that the relatively small population was disproportionately urban and consequently there weren't enough farmers in the region to grow food for everyone. Japanese calculations suggest that by 1945 yearly local production in Far Eastern Russia only covered 67% of bread-making grain, 66% of petroleum, and 38% of steel requirements. Hence, the balanced needed to be shipped from European Russia. Because the region's economy and the military forces stationed there both depended on the same Trans-Siberian railway, the more food, oil, and steel the Soviet regime shipped to the Far East, the less capacity would be available for military supplies in the event of war with Japan. Due to these limitations, Japanese planners estimated that the maximum size of any army force the Soviets could have fielded against them in the Far East at 55 to 60 divisions. (For comparison, the force the Soviets historically used in Manchuria in August 1945 - estimated by the Japanese at 1,600,000 men, 4,500 tanks, and 6,500 aircraft - was assessed as 47 divisions.) Further information can be found in JSOM vol. XIII (one of the 'special studies' prepared by the Japanese for the US Army after the war) where this subject is discussed in detail from page 17 onward.

.......Even though the Japanese army was divided and the Japanese navy generally opposed attacking the USSR, the "strike north" faction, led by General Shinichi Tanaka, ended up getting their way when it came to the size of the military buildup in Manchuria - on the condition that no actual attack would take place without Hirohito's authorization. However, when the Germans started to bog down in Europe and the Soviets failed to transfer half their Far Eastern forces westward the Japanese army started to consider the Kantokuen plan to be less attractive. The final nail in the coffin came on 1 August 1941 when the United States cut off all oil exports to Japan, followed by the Netherlands East Indies shortly thereafter. After this, the Japanese military formally decided on 9 August to concentrate on plans for an attack against Southeast Asia and the buildup in Manchuria and Korea was limited to only 16 divisions....
Thank you for that wealth of information in this post and your previous post.

In regards to the quoted section above though, wouldn't the US and NEI oil embargoes likely occur as in OTL as well in August 1941 even if the Japanese invaded the USSR?

What effect would this have on Japan and its campaign in the USSR?

I'm wondering if this wouldn't hobble their supply situation and if it might not make them look seriously at striking the Dutch East Indies and thereby have to consider taking out Singapore and Manila.....
 
Thank you for that wealth of information in this post and your previous post.

In regards to the quoted section above though, wouldn't the US and NEI oil embargoes likely occur as in OTL as well in August 1941 even if the Japanese invaded the USSR?

What effect would this have on Japan and its campaign in the USSR?

I'm wondering if this wouldn't hobble their supply situation and if it might not make them look seriously at striking the Dutch East Indies and thereby have to consider taking out Singapore and Manila.....
The United States likely would have enforced some kind of economic penalties on Japan in the event they invaded the USSR. On 21 October 1941 a memorandum prepared by Brigadier General Sherman Miles, acting Assistant Chief of Staff of U.S. Army G-2 [intelligence] made the following comments:
8. [...] "it is very much to our interest, so long as Russia continues to offer active resistance to Germany, to take whatever steps may be possible to maintain the present Russian equality in combat strength vis-a-vis the Kwantung Army. Two such practicable steps immediately present themselves:​
a. Increased aid to China, to enable the latter to continue to pin to the ground in North, Central and South China the bulk of the Japanese Army.​
b. Increased aid to the Russian armies both in Europe and Siberia."​

In my opinion, given Japan's dependence on foreign trade, the United States probably would have decided on an oil embargo (among other measures) as the most cost-effective way to achieve both (a) and (b) in the event of a Japanese attack on Siberia. Bear in mind, this memorandum was issued after the oil embargo was actually implemented, so the FDR Administration must have been considering additional steps, probably under the Lend-Lease act, which went into effect in March 1941.

The effects of the oil embargo on Japan's ability to fight a major land campaign would have been severe: after the embargo was actually implemented in August, the Japanese War Ministry estimated that if an invasion of Siberia took place they would run out of oil within six months to a year. Nakano Satoshi reports that in early August the "War Preparation Section" of the Army Ministry conducted a 're-simulation' of a previous study analyzing Japan's "National Physical Capabilities," this time under four scenarios:

1. Invasion of Siberia​
2. Invasion of Southeast Asia​
3. A Siege of Chungking​
4. Maintaining the status quo​

Although the original manuscript has yet to be rediscovered, the Japanese militarists discarded option 4 and apparently favored option 2 above the others, all of which involved armed force.

Considering the pattern of decisions made by the Japanese regime during that time, if they were hit by an economic embargo while already involved in a full-scale war against the Soviet Union and communist Mongolia, I consider it unlikely that they would have backed down and acceded to American demands. On the other hand, they wouldn't have been able to do much in the way of invading Southeast Asia either, at least until they reached their objectives in Siberia (defense line at the Great Khingan mountains). Despite that, depending on the timing of the hypothetical Japanese invasion, it might have been militarily possible for them to invade southeast Asia more or less when they did in real life, or perhaps with only a slight delay. In that case, the outcome would have depended on the state of Allied military preparedness, which, unfortunately, probably wouldn't have been much higher than it really was.

If the Japanese regime settled on that destructive course, the timing and eventual outcome of the wider war might have been tragically similar. With their Manchurian forces engaged in battle against the Soviets, however, their ability to reinforce the Pacific front or raise new units on the Japanese mainland would have been considerably reduced.
 
If the Japanese regime settled on that destructive course, the timing and eventual outcome of the wider war might have been tragically similar. With their Manchurian forces engaged in battle against the Soviets, however, their ability to reinforce the Pacific front or raise new units on the Japanese mainland would have been considerably reduced.
Could the war end sooner, and how much additional ground would Soviet forces gain?
 
The United States likely would have enforced some kind of economic penalties on Japan in the event they invaded the USSR. On 21 October 1941 a memorandum prepared by Brigadier General Sherman Miles, acting Assistant Chief of Staff of U.S. Army G-2 [intelligence] made the following comments:
8. [...] "it is very much to our interest, so long as Russia continues to offer active resistance to Germany, to take whatever steps may be possible to maintain the present Russian equality in combat strength vis-a-vis the Kwantung Army. Two such practicable steps immediately present themselves:​
a. Increased aid to China, to enable the latter to continue to pin to the ground in North, Central and South China the bulk of the Japanese Army.​
b. Increased aid to the Russian armies both in Europe and Siberia."​

In my opinion, given Japan's dependence on foreign trade, the United States probably would have decided on an oil embargo (among other measures) as the most cost-effective way to achieve both (a) and (b) in the event of a Japanese attack on Siberia. Bear in mind, this memorandum was issued after the oil embargo was actually implemented, so the FDR Administration must have been considering additional steps, probably under the Lend-Lease act, which went into effect in March 1941.

The effects of the oil embargo on Japan's ability to fight a major land campaign would have been severe: after the embargo was actually implemented in August, the Japanese War Ministry estimated that if an invasion of Siberia took place they would run out of oil within six months to a year. Nakano Satoshi reports that in early August the "War Preparation Section" of the Army Ministry conducted a 're-simulation' of a previous study analyzing Japan's "National Physical Capabilities," this time under four scenarios:

1. Invasion of Siberia​
2. Invasion of Southeast Asia​
3. A Siege of Chungking​
4. Maintaining the status quo​

Although the original manuscript has yet to be rediscovered, the Japanese militarists discarded option 4 and apparently favored option 2 above the others, all of which involved armed force.

Considering the pattern of decisions made by the Japanese regime during that time, if they were hit by an economic embargo while already involved in a full-scale war against the Soviet Union and communist Mongolia, I consider it unlikely that they would have backed down and acceded to American demands. On the other hand, they wouldn't have been able to do much in the way of invading Southeast Asia either, at least until they reached their objectives in Siberia (defense line at the Great Khingan mountains). Despite that, depending on the timing of the hypothetical Japanese invasion, it might have been militarily possible for them to invade southeast Asia more or less when they did in real life, or perhaps with only a slight delay. In that case, the outcome would have depended on the state of Allied military preparedness, which, unfortunately, probably wouldn't have been much higher than it really was.

If the Japanese regime settled on that destructive course, the timing and eventual outcome of the wider war might have been tragically similar. With their Manchurian forces engaged in battle against the Soviets, however, their ability to reinforce the Pacific front or raise new units on the Japanese mainland would have been considerably reduced.
Thank you again!

In addition to the relevant question @Johannes Parisiensis had asked, I would have to wonder if the Japanese might not indeed have been tempted to strike at Southeast Asia around the same time they did in OTL or perhaps even sooner. My reasoning being that in OTL the course of events went like this:

June 20, 1941 - United States announces that, henceforth, no petroleum would be shipped from the US east coast, or gulf coast ports, outside the Western Hemisphere (there was a shortage of fuel for domestic use on the east coast of the United States in June 1941 and it was untenable for the US government to ship fuel out of areas with shortages to semibelligerent foreign governments). Japan apparently views this as its supplies being slowly choked off.

July 21-29, 1941 - Japan occupies southern French Indochina, sparking further American concerns over Japanese intentions and contributing towards the oil embargo decision it seems and Roosevelts executive order.

July 26, 1941 - Roosevelt issues executive order freezing Japanese assets on about the same day that the Japanese make public their "voluntary agreement" with the French for Japanese troops to occupy southern Indochina.

August 1, 1941 - US oil embargo against Japan goes into effect (affecting 75-80% of Japanese oil imports apparently). Interestingly, the Dutch governor-general of the East Indies had urged the announcement of a joint Anglo-Dutch-American embargo on oil exports in a telegram from July 24 if the Japanese occupied southern French Indochina (p. 549).

August 5, 1941 - Acheson also includes blocking the release of Japanese funds, meaning Japan couldn't pay for oil even from the Dutch East Indies which was still willing to sell oil to Japan but only for cash, not credit (thus affecting basically 90% of Japan's oil imports).

At the time the Japanese concluded that they had 18-24 months (without an invasion of the Soviet Far East) worth of oil from what I've been seeing elsewhere and they accelerated their plans for Southeast Asia (and as you noted the thinking in Japan seemed to be that simply seizing the Netherlands East Indies alone was not an option and they had found British War Cabinet minutes that attempting to do so would bring in the British in anyway, plus they were concerned that US forces in the Philippines could cut off Japanese supplies from the British/Dutch East Indies to Japan proper hence the view to remove that threat too...) so as to invade in December 1941. So with a Japanese invasion of the USSR in conjunction with Germany we might see an oil embargo TL like this:

June 20, 1941 - United States announces that, henceforth, no petroleum would be shipped from the US east coast, or gulf coast ports, outside the Western Hemisphere (there was a shortage of fuel for domestic use on the east coast of the United States in June 1941 and it was untenable for the US government to ship fuel out of areas with shortages to semibelligerent foreign governments). Japan apparently views this as its supplies being slowly choked off.

June 26, 1941 - Roosevelt issues executive order freezing Japanese assets following Japanese invasion of Soviet Far East

June 28, 1941 - US oil embargo against Japan goes into effect (affecting 75-80% of Japanese oil imports apparently)

July 3, 1941 - Acheson also includes blocking the release of Japanese funds, meaning Japan couldn't pay for oil even from the Dutch East Indies which was still willing to sell oil to Japan but only for cash, not credit (thus affecting basically 90% of Japan's oil imports).......


At this point, fighting is already underway in the Soviet Far East and as you pointed out the Japanese would have then estimated that it would be 6 months (January 1942) before they ran out of oil with which to conduct the campaigns. Going after the Dutch East Indies in December 1941 would then in theory be cutting it close (especially if fighting in the Soviet Far East is tougher than expected which might cause them to revise their estimates downwards slightly).

In that case, might the Japanese not aim to start a Southeast Asia campaign earlier, like say in November 1941?
 
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In that case, might the Japanese not aim to start a Southeast Asia campaign earlier, like say in November 1941?
I think that would have consequences for the attack on Pearl Harbor. They needed the Shokaku and Zuikaku, which weren't ready earlier. So either the attack goes with 2 less carriers, or they attack somewhere else.
 
I think that would have consequences for the attack on Pearl Harbor. They needed the Shokaku and Zuikaku, which weren't ready earlier. So either the attack goes with 2 less carriers, or they attack somewhere else.

Are you sure? This article (always take with a grain of salt) has the Shokaku being completed on August 8, 1941 and the Zuikaku being completed on September 25, 1941. The operation for Pearl Harbour itself was gamed out in September or October I believe after it was proposed by Yamamoto.
 
Are you sure? This article (always take with a grain of salt) has the Shokaku being completed on August 8, 1941 and the Zuikaku being completed on September 25, 1941. The operation for Pearl Harbour itself was gamed out in September or October I believe after it was proposed by Yamamoto.
Usually after being completed a ship takes seatrials. So it's going to be tight.

In earlier discussions about the Pearl Harbor others posted that the Shokaku and Zuikau were just in time to be ready for the attack.
 
I am not sure I agree with the premise. The Japanese Army high command was fixated on China but what if there were to view their position more objectively. They could have just accepted a stalemate and it is even possible Chiang Kai-shek would have accepted a truce. There certainly is no reason to suspect Chiang would have been any more active in response to a Japanese stand down or lessening of activity. There may have been a Soviet initiative for an attack against the Japanese in Burma. To me the decreased flow of Lend Lease supplies would be the most significant factor.
After fighting the Japanese invaders for years at that point, and Japan's position in China weakening in this way there's no way the Chinese won't take advantage (if only for one faction to look good at the expense of the other*)! This is actually one of the ongoing concerns in the Japanese army in general. Risking what they spent years fighting and dying for in China to solve problem elsewhere. They resisted internal and international pressure to remove troops from French Indochina etc to ease the political situation with the US for the same reason. This all becomes embroiled in the political moves going in Japan's government in 1941.

I.e. the Japanese army command with it substantial political position is fixated on and unlikely to look objectively at China. Because it's been fighting, dying and doubling down on atrocities there for years, all after promising a quick easy victory against a inferior enemy (huh now that sound's familiar).

Actually all that political turmoil in 1941 is another reason why Japans is unlikely to go for it in Russia just in time to save the Germans initial plan!


*and of course the corollary is if either faction in China is seen to be making peace the other will point and shout at that.
 
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In 1940 no one knew there were oceans of oil under Siberia. The IJN wanted to go south for the oil, going north means no oil, rubber and other minerals.

What happens when the embargo gets ramped up and the US starts buying up all of those resources Japan needs and can't get. I figure the IJA gets tired marching everywhere as there is no fuel for their trucks or tanks. The Russian Army is a very different beast in 1942 and has T34 and well trained crews. I can't think of anything less likely to stop a Russian Tank Heavy formation than Japanese light infantry.
 
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