Secrets of the Dead S09E04 - Japanese SuperSub

Japanese SuperSub recounts Japan's superior submarine technology and reveals how close the Japanese came to using the subs to blow up the Panama Canal, terrorize the U.S. and possibly enact a deadly biological attack. The supersub, obtained by the U.S. at the end of the war, combined the tactical advantages of sea and sky. But why did America sink one of its most prized military captures?