“Even when heavy enemy battle losses are substantiated, one must be careful not to judge their psychological effect on the bassis of occidental values. Indeed, American military professionals who fought in the Pacific during World War II or in Korea became acutely aware of differing oriental values with respect to human life, and knew the pitfalls of putting too much store in the impact of heavy casualties on the morale of a determined foe or on the will of a ruthless totalitarian government.”