The Battle of Khalkin Gol took place in 1939 May - Sep and was the last border battle between Japan and USSR. It was a major victory for the Soviets.

But the Soviet–Japanese Neutrality Pact was not signed until 1941 Apr 13.

What took so long? I would have thought Japan at least would want to secure the peace so it could hold onto Sakhalin, Kurils, and of course Manchuria. And it's not like USSR wasn't busy in Europe during all that time, e.g., the invasion of the Baltics and part of Poland as per the Molotov-Ribbentropt Pact, and the Winter War with Finland in 1939 - 1940.

I'll also note the Soviet-German non-aggression Pact was signed in 1939 Aug 23, so I don't see why the Japanese didn't happen around the same time. I'll also note that Barbarossa didn't happen until 1941 Jun 22, so it's not like the Soviets waited until the war with Germany was underway to become desparate for securing peace in on their east border.

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The Soviet-Japanese Neutrality Pact was not signed because they bloodied each other's noses and were done. It was signed because both sides knew they were about to go to war. The Soviets with Germany and Japan with the US. Both sides were eager to secure their flank from the other.

On the Japanese side there was a debate between a northern and southern strategies. The army backed Hokushin-ron aimed at China, Manchuria, and Siberia. The navy backed Nanshin-ron aimed at Indochina and the South Pacific.

Khalkhin Gol spelled the decline of Hokushin-ron, but it took some time for this to be fully abandoned, for the navy to gain supremacy, and for tensions with the US to reach a boiling point.

The Soviets and Germans had no illusions that the Molotov-Ribbentrop Pact would hold. Hitler was very clear about his contempt for the Slavs and plans to expand eastward. The Soviets were eager to delay the coming war with Germany as long as possible to give themselves more time to prepare, something made very acute after their humiliation in the Winter War with Finland. The Germans wanted to secure their Eastern flank while they were stomping around Western Europe and Scandinavia, as well as secure valuable resources that would be cut off in the inevitable Allied blockade.

The Soviets were riding a knife edge with Germany. On the one hand, there were talks of the Soviet Union joining the Axis in late 1940, but these went nowhere. On the other hand, German and Soviet paranoia meant any move could be seen as hostile. A Soviet treaty with Japan could been seen as strengthening ties with the Axis, or it would be seen as securing their flank in preparation for war with Germany.

Once Japan joined the Axis in late 1940 it became more clear that a treaty with Japan would be seen, publicly anyway, as a gesture of goodwill and peace towards the Axis. The Soviets ultimately decided to negotiate a treaty. Meanwhile Germany had already decided to invade.

  • This is incorrect. Germany was at the Gates of Moscow when Japan "knew" they would start an unprovoked and Total War with the United States(sic). No one knows WHY this happened....but certainly Nazi Germany celebrated big-time since they had been stopped stone cold by the Russians at Moscow and if Japan simply did nothing Hitler was SCREWED. Needless to say the Germans were not ASKING for help either as "Victory was both assured and imminent!" (Maybe by 1945...) If Japan had attacked Russia...a devious and dastardly thing indeed....there would have never been a USSR anymore that's for sure... Oct 31, 2016 at 2:28
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    @user14394 I often have trouble connecting your comments to the question or the answer. Sometimes I wonder if you're a decently written bot.
    – Schwern
    Oct 31, 2016 at 3:27

What I got from War in the Far East volume 1, by Harmsen is that, in mid 1939, Japan was not only wanting to insulate itself from USSR risks, it was hoping for an expanded German-USSR-Japan axis to allow a unified stance against the powers Japan was either at war with or potentially hostile to:

China, USA, UK

In other words, it didn't them 2 years to draw a line under Khalkin Gol and expanding into Russia. It took them 2 years to get to a point where they partially committed to good relations with Russia with the hope of closer relations on an expanded Axis, including Russia, because they were already buddies with Germany.

Apparently, once they knew of Barbarossa, they told Russia they'd not have signed it if they knew Germany's intentions. That can be either because they'd have wanted to participate in that attack. Or because they knew the Japan-Germany-Russia axis was futile.


I think the answer is how Japan viewed the Molotov-Ribbentrop pact. Japan was moving toward war with the USSR thinking Germany was doing the same.

After the defeat at Khailkhin Gol, Japan knew it would need a larger commitment. With the pact, Japan also knew it could not count on Germany. That is, had Japan attacked the USSR after Germany invaded, the fear was that Germany would make peace with the USSR. Japan waited to make peace because it wanted to keep the world guessing.

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