The “infamy” of December 7, 1941, is deeper than most Americans have ever imagined. The Japanese attack on Pearl Harbor was almost certainly the result of a Soviet plot—“Operation Snow”—carried out by Harry Dexter White, a figure of enormous influence in the Roosevelt administration and a known Soviet spy. Americans remember Pearl Harbor as the work of a Japanese military machine hell-bent on a war of conquest. The truth is more complicated. The imperial regime had faced severe political shocks throughout the 1930s. Two attempts on the life of Emperor Hirohito—one by a Japanese communist whose father was a member...