Why Japan backed down before 1941

Japan's restraint at Tsingtao resembles its retreat during the Asama Maru incident in January 1940. Senior leaders understood that an escalation could bring the full British and American naval balance against Japan. By 1941, sanctions were biting while British forces had been drawn down by war in Europe, creating a brief and dangerous opportunity. The decision for war depended on timing and perceived alternatives rather than an unchanging Japanese willingness to attack.