No sources at all, that I can find.
So much for Coleman.
Both Prange and Victor discuss Dusko Popov, code name Tricycle, and his meeting with J. Edgar Hoover.
Prange does not, but Victor does claim that Hoover reported Popov's interest in Pearl Harbor to President Roosevelt.
But even Victor (c2007) does not purport to quote from a conversation where FDR dismissed Hoover's warning.
We should note that Hoover had long been wire-tapping the Japanese consulate in Hawaii, and well knew of their interest in the US fleet, and would doubtless have reported it to President Roosevelt.
This is explained away as being nothing more that "routine" espionage, of the kind every nation did on all others.
But Popov's interest in Pearl Harbor was of a different nature, and should have excited more interest at top levels of the US government than it did, imho.
My copy of Coleman's book is a Kindle PC version, and I had not noticed before that he apparently included no references to source material.
WTF?
So, until I can learn something new about it, I'm inclined now to just cross Coleman off as nothing more than a toxic collection of rumor and innuendo...
If it makes you feel any better, this is the same Dr. Coleman who claims that MI-6 was charged with, and executed the assassination of John F. Kennedy and Abraham Lincoln. Mind you, MI-6 did not exist in 1865, but what the hell. He also makes the claim that the HIV virus was developed at Harvard University and spread by the WHO under the guise of the eradication of Small Pox. Apparently they were infecting them with HIV at the same time they were vaccinating them. He’s an interesting character.