The Imperial Japanese Navy made its surprise attack on Pearl Harbor, Oahu, Hawaii Territory, on Sunday morning, December 7, 1941. The Pacific Fleet of the United States Navy and its defending Army Air Forces and Marine air forces sustained significant losses. The primary objective of the attack was to incapacitate the United States long enough for Japan to establish its long-planned Southeast Asian empire and defensible buffer zones. However, as Admiral Yamamoto feared, the attack produced little lasting damage to the US Navy with priority targets like the Pacific Fleet's aircraft carriers out at sea and vital shore facilities, whose destruction could have crippled the fleet on their own, were ignored. Of more serious consequences, the U.S. public saw the attack as a treacherous act and rallied against the Empire of Japan. The United States entered the European Theatre and Pacific Theater in full force. Four days later, Adolf Hitler of Germany, and Benito Mussolini of Italy declared war on the United States, merging the separate conflicts. Following the attack on Pearl Harbor, the Japanese launched offensives against Allied forces in East and Southeast Asia, with simultaneous attacks on British Hong Kong, British Malaya and the Philippines.
By the time World War II was in full swing Japan had the most interest in using biological warfare. Japan's Air Force dropped massive amounts of ceramic bombs filled with bubonic plague infested fleas in Ningbo, China. These attacks would eventually lead to thousands of deaths years after the war would end.[5] In Japan's relentless and indiscriminate research methods on biological warfare, they poisoned more than 1,000 Chinese village wells to study cholera and typhus outbreaks. These diseases are caused by bacteria that with today's technology could potentially be weaponised.[6]