[dfwgator]

But the agreement to invade was made before the Nazis rolled, so the Soviets are jointly responsible.

[jamaksin]

Notwithstanding the German-USSR non-aggreesion pact (executed on August 23, 1939), the question was event which "started" World War Two.

It was not the signing of the said non-aggression pact, nor Japanese actions, but rather German troops crossing the Polish frontier.