Poland 1939....

[Lucky13]

Why wasn't war declared on Soviet Union, when they attacked Poland on the 17th of September 1939, as it was on Germany roughly two weeks before?

 

[michaelmaltby]

both Britain and France were favorably disposed to the USSR ... in a ham-handed, slow boat, limp wristed kind of a way .... even after Molotov-Ribentropp there was some misguided notion of signing a non aggression pact with the Soviets. Remember, the time window you speak of, the USSR had yet to play the territorial gains card it had won from Hitler .... the 3 Baltic Republics, and parts of Romania.
... in September, 1939, Stalin's 'position' was seen as less aggressive and purely defensive.
In early negotiation with Britain and France, Stalin had offered to 'contain' Hitler ... for the price of deploying westward into Polish territory.
Request was denied at the time .... but that's what he indeed did in September, 1939.

 

[BOBIBEAN]

both Britain and France were favorably disposed to the USSR ... in a ham-handed, slow boat, limp wristed kind of a way .... even after Molotov-Ribentropp there was some misguided notion of signing a non aggression pact with the Soviets. Remember, the time window you speak of, the USSR had yet to play the territorial gains card it had won from Hitler .... the 3 Baltic Republics, and parts of Romania.
... in September, 1939, Stalin's 'position' was seen as less aggressive and purely defensive.
In early negotiation with Britain and France, Stalin had offered to 'contain' Hitler ... for the price of deploying westward into Polish territory.
Request was denied at the time .... but that's what he indeed did in September, 1939.

Also, the Soviets were soon "negotiating" new borders with ex-Tsarist territory of Finland to protect themselves from a springboard attack from mostly Britain....

 

[michaelmaltby]

... at this point in the shuffle, Stalin feels very confident that he has the upper hand with Hitler, he will continue in this aggressive mode ... pushing for more of Romania and Lithuania ... than Hitler had bargained/staked.
All this attitude will change with the Fall of France ... Stalin had never imagined it possible. He woke up!

 

[George88]

Why wasn't war declared on Soviet Union, when they attacked Poland on the 17th of September 1939, as it was on Germany roughly two weeks before?

Because in 39 SU dont occuped polish teritory but eliberated their own that Poland occuped in 1920 today Belarus and western Ukraine

 

[Crimea_River]

Let the games begin....

 

[michaelmaltby]

"... Why wasn't war declared on Soviet Union, when they attacked Poland on the 17th of September 1939, as it was on Germany roughly two weeks before?"

Simple answer: Britain and France were shell-shocked from M-R Non Aggression bombshell. Both countries had been ham-fistededly, incompetently, insincerely trying to negotiate a Pact with Stalin - right up to the day M-R was announced.

And Russia was slow off the mark getting into Poland, it was a horse drawn army that finally connected with the Heer. The Soviet action didn't attract much attention except for Polish Jews who tried to move towards the Soviets ..

 

[Admiral Beez]

And Russia was slow off the mark getting into Poland,

Now, if the Russians invade Poland before the Germans, then what do France and Britain do?

And what if, as the Germans fear the Russians don't stop at Poland and carry on into Germany. Now who's Britain and France's ally in Europe?

 

[Capt. Vick]

The friend of my enemy, is my friends first cousin, twice removed?

 

[tomo pauk]

Why wasn't war declared on Soviet Union, when they attacked Poland on the 17th of September 1939, as it was on Germany roughly two weeks before?

War was not declared universaly, but by UK and France. But, in a more affirmative tone, both UK and France didn't wanted to be involved in a war against both Germany and USSR, since there is no way that they could've come on top, even by 1939 standpoint.