the 1939 invasion of Poland was by both Soviet union and Nazi Gemany, why did the Allies ignored Soviet army invading?

The best answer in my opinion is that the West expected that the relations between Hiter and Stalin would one day collapse and after that the USSR was in their camp, so " do not irritate the bear!"....

That is also the reason the West did not react with military power as the USSR attacked Finland or took the Baltic countries.

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Also in the Poland case the USSR diplomacy was skilfull enough to make it pass as a reclaiming of lost territory in the Russo-Polish war of 1921

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Now that is a very good question since Great Britain and France made a promise to defend Poland if she was attacked. Now I would think and history shows that this was aimed more towards Nazi Germany and they did not think that the USSR would have attacked Poland. Now this brings up an interesting 'What if'. What if Great Britain and France also declared war on the USSR because of the treaty signed with Poland. How would that have changed the direction of the war?

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American by birth, TEXAN by the grace of GOD!

indeed strange thing. you would have expected after Versailles that they would declare war to the USSR. but didn't chamberlain wanted to keep out off the war and was afraid to attack. he had the promise from Hitler.

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Sixty-four bomber pilots and crew lie in the cemetery at Wevelgem Communal and today many locals still pay their respects to those brave men from high in the skies.

The Soviets invaded 17 days after the German invasion, Britain and France were already at war with Germany, the last thing they needed was to get involved in a war with another major power.

Principles are fine and dandy, but they are sometimes a luxury you cannot afford.

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if in doubt....Panic!!!!

France kicked around the question for several days, but decided not to because it would have just been words, there was nothing that could have been done to Russia had war been declared.

Now if the war in the west had gone the allies way, ie quick german defeat, I think that the issue would have been revisited. Still very interesting stuff.

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The Muslim Brotherhood “must understand that their work in America is a kind of grand Jihad in eliminating and destroying the Western civilization from within and ‘sabotaging’ its miserable house by their hands..." — Mohamed Akram. http://jihadwatch.org/

To further confuse the issue, I don't think the USSR even declared war on Poland, they just "advanced to occupy former territory".

Ditto with Bessarabia. See this.

And remember France and the UK were at the time large Colonial Powers (as my own country was), so they had their own closets crammed full of skeletons, so any argument would be easy to counter.

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In the Winter War 1939-1940 Stalin even invented the "new government" for Finland that asked for help from the USSR....

"The "People's Government" was created to help Stalin's political and military goals in his attempt to conquer Finland."

Otto Ville Kuusinen

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I´m well aware of that episode. I can't help imagining Stalin giggling to himself imagining new tricks to screw the other guy.

It must take a twisted sense of humour, but a sense of humour it has to be, for sure!

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which kind of diplomacy? it seems likely Soviet Union diplomatic relation were pretty much cut off from Allies at the time. Germany also had territorial claims over poland and border disputes form Versailles.
Still Warsaw surrounded 10 days after Soviet troops invaded form east. France and England to fulfill their territorial guarantees to Poland must have come under defense of Poles. and does not matter that they were major or minor, the response to the invasion of Poland must have been the same.
so? German forces invade Poland without a declaration of war in 1 September

There was a plan to help Finland against Russia

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Coir a glaive

Nemo me impune lacessit

And we do know rather well that the troops would have stopped in Northern Sweden to take the iron ore mines in Kiruna to stop the Germans from getting their iron ore. Not going to Finland to help...

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Sure, but it was a plan

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Coir a glaive

Nemo me impune lacessit