Actually he was late. The media had already been infected by the commies and controlled the narrative.
The USSR should never have been able to flourish post war but that was FDR’s gift to America. I hate Commies and all of their spawn we have today.
Whittaker Chambers, Walter Krivitsky and others provided the FDR administration with details of Soviet penetration of our government in 1939, but the administration refused to act. Had they nailed Alger Hiss & Co. at that time, the latter decades of the 20th century would have been happier for the whole world.