AAQ: �I would be careful claiming that Rebbe killed Stalin. Why didn�t here do it earlier before millions of people were killed?�
The story with Stalin unfolded at a farbrengen , it�s no secret, you can look it up easily I�m sure
The Rebbe is fighting Hashem�s battles and cannot do anything before the time Hashem wills.
A deeper reason could be that The Rebbe wasn�t appointed as moshiach yet before then.