Analysis of information sources in references of the Wikipedia article "Soviet invasion of Poland" in English language version.
In September, even before the start of the Nazi atrocities that horrified the world, the Soviets began their own program of systematic individual and mass executions. On the outskirts of Lwów, several hundred policemen were executed at one time. Near Łuniniec, officers and noncommissioned officers of the Frontier Defence Cops together with some policemen, were ordered into barns, taken out and shot ... after December 1939, 300 Polish priests were killed. And there were many other such incidents.
It is worth clarifying that the Nazi-Soviet Pact was not an alliance as such, it was a treaty of non-aggression. Consequently, aside from the metaphorical tide used here - The Devils' Alliance - I generally refrain from referring to Hitler and Stalin as 'allies' or their collaboration as an 'alliance'. However, that clarification should not blind us to the fact that the Nazi-Soviet relationship between 1939 and 1941 was a profoundly important one, which consisted of four further agreements after the pact of August 1939 and was, therefore, close to an alliance in many respects. Certainly it was far more vital and far more crucial to both sides than, for instance, Hitler's alliance with Mussolini's Italy. Hitler and Stalin were allies in all but name.
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ignored (help)The Soviet Union participated as a cobelligerent with Germany after 17 September 1939, when Soviet forces invaded eastern Poland
As a co-belligerent of Nazi Germany, the Soviet Union secretly assisted the German invasion of central and western Poland before launching its own invasion of eastern Poland on 17 September
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: CS1 maint: multiple names: authors list (link)The Soviet Union participated as a cobelligerent with Germany after 17 September 1939, when Soviet forces invaded eastern Poland
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ignored (help)The Soviet Union participated as a cobelligerent with Germany after 17 September 1939, when Soviet forces invaded eastern Poland
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