That... is total conspiracy nonsense. It's pretty clear that Stalin was in charge right up until the moment he had that final stroke. Even while he was lying on the floor dying, his inner circle was too terrified to suggest someone else take power. The Doctors Plot was a result of the same paranoia which oversaw the Great Purges, but it wasn't the actions of a madman. Otherwise, Stalin's foreign policy was consistent and rational, as expressed in both words and actions: preserve the existence of the "Workers State", consolidate existing gains from the last war, probe the West for further gains at a minimal cost, and prepare for the future war when the Capitalists will attack, which is supposed to be inevitable, while simultaneously delaying that war as much as possible.