Who Started World War II?

[ikalugin]

Would that be the same Soviets that attacked Warsaw and were defeated nineteen years prior?

Same Soviets.
Same Russians that have partitioned Poland with Germans and Austrians.
Same Poles that were sitting in My Kremlin 336 years before the events of 1939 (discounting Polish troops under Napoleon).

One could always dig deeper. Plus in 1939 Poles were dreaming about a great empire of sorts and didn't know about General Plan East. So that suggestion was entirely retrospective.