I haven't read the book you reference. However, my book on the subject was written after General deWitt's recommendations to President Roosevelt had been declassified. In those documents, deWitt made the incredible argument that 1) there were no known instances of Japanese-American sabotage, and 2) that lack of any sabotage was proof that they were "well organized" and therefore "dangerous."
It was on the basis of deWitt's report, with the support of Governor Earl Warren of California, that President Roosevelt issued his Executive Order. (I think that Warren became a screaming liberal as Chief Justice in part as expiation for supporting both the internment of the Japanese-Americans, and also a prior California law that made it illegal for the Nissei to own farm land in California.)
It doesn't matter to me what anyone wrote about this situation without access to the WW II internal documents. I had those documents, and got some of them declassified for my book. I stand by my historical and constitutional conclusions on this subject.
Congressman Billybob
Click for latest column for UPI, "Those in Peril on the Sea" (Now up on UPI wire, and FR.)
As the politician formerly known as Al Gore has said, my book, "to Restore Trust in America"
This is the classic conspiracy-nut argument -- the absence of evidence proves that the Evil Conspiracy has a tentacle in every pie, and managed to destroy or suppress every clue.
Through the war and the Cold War that followed it, the Anglo-American history of decryption was one of the most closely held secrets of government. Sanitized reasons (DeWitt's racism) had to be found for internment. Guilty Japanese could not be brought to trial when the evidence had to be kept secret.