National Security
An overview of what various nations would consider tolerable international conduct, 1936-41.
Spheres of Interest
The following were the approximate spheres of interest of the various nations. Interfering in a sphere of interest would have caused anything from alarm to a declaration of war depending on the relative power of the interferer and the extent of their action.
Great Britain - most of the world, barring perhaps Mongolia/ Tannu Tuva /Siberia/Xinjiang.
France - countries neighboring French territories, Central & Eastern Europe.
Germany - countries neighboring German territories, Europe.
Italy - countries neighboring Italian territories, Mediterranean.
USSR - countries neighboring USSR.
Japan - countries neighboring Japanese territories, East and Southeast Asia.
USA - Americas, Greenland, Philippines, eastern China, Southeast Asia.
China - territories composing former Chinese Empire, including Manchuria, Mongolia, Tannu Tuva , Xinjiang, and Tibet.
Small countries - immediate neighbors.
Note that only Japan, USSR, and other warlords would have been likely to intervene against moves by Chinese warlords or Tibet. Pre-1937, Japan intervened in the Northeast south to Shanghai and west into Inner Mongolia. From the 1930s to 1954, the USSR interfered in Xinjiang and involved itself in Mongolia's border disputes with China and Manchukuo. Britain was the other major intervener in China, but avoided confrontation except when its concessions were threatened.
Spheres of Influence
The following were the approximate spheres of influence of the various nations. Interfering in a sphere of influence would have led to a warning followed by a declaration of war in most cases.
Great Britain - the Americas & Greenland (in support of the US), Iceland, Ireland, Belgium, Holland, Norway, Denmark, France, Spain, Portugal, Egypt, South Africa, the Middle East (might have accepted a Saudi invasion of Yemen), Iran, Afghanistan?, Thailand (esp. Kra isthmus), Dutch East Indies, Australia, NZ.
USSR - Eastern Europe, Turkey?, Iran?, Afghanistan?, Mongolia.
Japan - Manchuria.
USA - Americas, Greenland, Philippines.
A transport loaded with troops and headed into the Atlantic, or in the general direction of a British colony, would have been intercepted and stopped by the Royal Navy.
For instance, in February/March 1941, British colonial governments were advised to authorise military counter measures if the Japanese were to move into Thailand west of 100°E or south of 10°N or their warships were to move towards the Kra isthmus or cross the 6°N parallel between Malaya and Borneo. [1]
The Monroe Doctrine and Western Hemispheric Security
US isolationism was a policy that essentially only applied to wars outside the Americas. Were a foreign imperial power to attempt to assert control over a part of the Western Hemisphere (including Greenland), the US would almost certainly respond militarily and with the support of other American states. In such a case, the British would probably also join in support.
Likewise, if one Latin American state were to attempt to conquer another, that state would have been met by an alliance of US-backed neighbors. The forming of coalitions to block expansionism was a constant feature of Latin America after independence. Since the late 19th century, coalition wars were replaced by US intervention and insistence on mediating over border disputes. The sentiment for isolationism did not contradict this - while avoiding World War I, for example, the US sent military expeditions to Mexico, Nicaragua, Haiti, and the Dominican Republic. Although interventionism was renounced in the Good Neighbor Policy of 1933, this policy in itself was aimed to reduce Latin American resentment and help unify the hemisphere in the face of potential foreign aggression.
The Soviet Union
The Soviet Union vs Germany
The Soviet Union would never have surrendered. Compare Stalin with Lenin and Chiang Kaishek. Despite unbelievable reverses in the Russian Civil War (Lenin) and the Sino-Japanese War (Chiang), both of these leaders fought on. Stalin was arguably more ferocious than either of these two and his USSR had more to lose. Lenin was facing the defeat of his revolution; Chiang, the recognition of puppet states; whereas Stalin was looking at the potential enslavement and extermination of his people.
The best peace terms that Germany could have got, without the war to the death that Hitler wanted, would probably have been something akin to Brest-Litovsk where the USSR acknowledged the "independence" of the non-Russian SRs. Lenin only accepted the terms of Brest-Litovsk because he had no army, and even then it was deeply unpopular. It seems unlikely that Hitler would have accepted a Brest-Litovsk prior to Stalingrad (if then) or that Stalin would have agreed to one after then.
There is simply no way that a Soviet leader would have accepted a western border at the Urals so long as they held territory to the west. They had all fought in the Civil War and knew the near-impossibility of reconquering Russia from Siberia.
The Soviet Far East
Siberia and the Far East, on the other hand, were more expendable. If a combined east-west offensive imperiled the existence of the USSR, it would probably have opted to cede large territories in the east until it could consolidate its hold on the west (similar to what happened in the Russian Civil War).
Depending on the composition of the invaders, such cessions might have included a combination of the following: "returning" Outer Manchuria and Vladivostok to Manchukuo, North Sakhalin to Japan, part of central Asia to Xinjiang, recognising the "independence" of a Far Eastern republic extending from Irkutsk or Baikal to perhaps Kamchatka and Chukotsk, recognising an "independent" Yakutia, and/or accepting Japanese influence over an enlarged Mongolia (Inner, Outer, Tannu Tuva , ...?). Historically, a few of these cessions would probably have been enough to satisfy Japan. It's main aim was to protect the home islands and Manchuria - once a suitable buffer had been established, it would probably have been more interested in preserving a weakened but independent Russia than in conquering Siberia.
Integrity of China
Tibet, Xinjiang, Tannu Tuva , Mongolia, and Manchuria were considered integral parts of China by both the KMT and the CCP. While a Great Power might have intervened in these areas without creating a war with China, any such act would have resulted in Chinese resentment (and probable denouncement by the US).
Southeast Asia
In 1922, Japan guaranteed the inviolability of the Dutch East Indies as part of a general agreement with the US, Britain, France and Holland to maintain the status quo in Southeast Asia.
US Attitude
With the exception of granting colonies independence, the US frowned upon any attempts to alter the 1922 status quo. Even the perfectly reasonable attempt by Siam to renegotiate its borders with [Vichy] French Indochina was met with unflinching US opposition, even though the British made efforts to persuade them otherwise.
Despite this attitude, the US refused to make any solid security guarantees to either the British or the Dutch. By July 1941, in the wake of Barbarossa, the US decided it would would respond to the next overt Japanese act with an economic embargo. This overt act was to be the Japanese push into southern Indochina later that month.
The Japanese move into Southern Indochina and the US Embargo
On July 23, Vichy permitted Japan to establish naval and air bases in Southern Indochina (troops began landing on July 28 - prior to this Japanese control did not extend south of Hanoi on the game map (an important historical detail that HOI2 ignores)). On July 26, FDR responded by freezing Japanese assets in the US. On August 17, the Japanese were told that if they took further steps toward military domination of their neighbors, the US would do whatever it deemed necessary to safeguard US interests. On December 3, FDR commented to the British that a Japanese attack on the Dutch East Indies would be easy to present to the US public as a threat to encircle the Philippines. This was enough to instill confidence in the British that America would join them in coming to Dutch aid if the East Indies were invaded.
The US response to Japan's move into southern Indochina was rather severe given that Japan was already in the north and the deployment of its troops south met no French resistance (indeed, the US acted before Japan actually moved in). This suggests that any further major act of aggression on Japan's part would have been met by war with the US. That realisation, plus the impact of the embargo, may have been instrumental in determining that Japan's next attack would fall on Pearl Harbor rather than Vladivostok (as British intelligence had believed in July).
Footnotes
- ↑ Tarling, Nicholas (1996). Britain, Southeast Asia and the onset of the Pacific war . Cambridge University Press. p. 225. ISBN 0-521-55346-6.