Soviet invasion of Manchuria in the context of "Atomic bombings of Hiroshima and Nagasaki"

Japan's Kwantung Army invaded the Manchuria region of China on 18 September 1931, immediately following the Mukden incident, a false flag event staged by Japanese military personnel as a pretext to invade. At the war's end in February 1932, the Japanese established the puppet state of Manchukuo. The occupation lasted until mid-August 1945, towards the end of the Second World War, in the face of an onslaught by the Soviet Union and Mongolia during the Manchurian Strategic Offensive Operation.

With the invasion having attracted great international attention, the League of Nations produced the Lytton Commission (headed by British politician Victor Bulwer-Lytton) to evaluate the situation, with the organization delivering its findings in October 1932. Its findings and recommendations that the Japanese puppet state of Manchukuo not be recognized and the return of Manchuria to Chinese sovereignty prompted the Japanese government to withdraw from the League entirely.

The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, ending the war. By the end of July 1945, the Imperial Japanese Navy (IJN) was incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of Japan in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction". While publicly stating their intent to fight on to the bitter end, Japan's leaders (the Supreme Council for the Direction of the War, also known as the "Big Six") were privately making entreaties to the publicly neutral Soviet Union to mediate peace on terms more favorable to the Japanese. While maintaining a sufficient level of diplomatic engagement with the Japanese to give them the impression they might be willing to mediate, the Soviets were covertly preparing to attack Japanese forces in Manchuria and Korea (in addition to South Sakhalin and the Kuril Islands) in fulfillment of promises they had secretly made to the US and the UK at the Tehran and Yalta Conferences.

On 6 August 1945, at 8:15 am local time, the United States detonated an atomic bomb over the Japanese city of Hiroshima. Sixteen hours later, American president Harry S. Truman called again for Japan's surrender, warning them to "expect a rain of ruin from the air, the like of which has never been seen on this earth." Late on 8 August 1945, in accordance with the Yalta agreements, but in violation of the Soviet–Japanese Neutrality Pact, the Soviet Union declared war on Japan, and soon after midnight on 9 August 1945, the Soviet Union invaded the Japanese puppet state of Manchukuo. Hours later, the U.S. dropped a second atomic bomb on the Japanese city of Nagasaki.

The Workers' and Peasants' Red Army, often referred by its shortened name as the Red Army, was the army and air force of the Russian Soviet Republic and, from 1922, the Soviet Union. The army was established in January 1918 by a decree of the Council of People's Commissars to oppose the military forces of the new nation's adversaries during the Russian Civil War, especially the various groups collectively known as the White Army. In February 1946, the Red Army (which embodied the main component of the Soviet Armed Forces alongside the Soviet Navy) was renamed the "Soviet Army". Following the dissolution of the Soviet Union it was split between the post-Soviet states, with its bulk becoming the Russian Ground Forces, commonly considered to be the successor of the Soviet Army.

The Red Army provided the largest ground force in the Allied victory in the European theatre of World War II, and its invasion of Manchuria assisted the unconditional surrender of Japan. During its operations on the Eastern Front, it accounted for 75–80% of the casualties that the Wehrmacht and Waffen-SS suffered during the war, and ultimately captured the German capital, Berlin.

The Hirohito surrender broadcast (Japanese: 玉音放送, Hepburn: Gyokuon-hōsō; lit. 'Broadcast of the Emperor's Voice'), was a radio broadcast of surrender given by Hirohito, the emperor of Japan, on August 15, 1945.

With historic understatement, it announced to the Japanese people that as "the war situation has developed not necessarily to Japan's advantage", the Japanese government had accepted the Potsdam Declaration, which demanded the unconditional surrender of the Japanese military at the end of World War II. Following the Hiroshima bombing on August 6, and the Soviet declaration of war and Nagasaki bombing on August 9, the Emperor's speech was broadcast at noon Japan Standard Time on August 15, 1945, and referred to the atomic bombs as a reason for the surrender.

Operation Downfall was the proposed plan by United States and British Commonwealth forces for the invasion of the Japanese home islands near the end of World War II. It was canceled when Japan surrendered following the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the invasion of Manchuria.

The operation had two parts: Operation Olympic and Operation Coronet. Set to begin in November 1945, Operation Olympic was intended to capture the southern third of the southernmost main Japanese island, Kyūshū, with the recently captured island of Okinawa to be used as a staging area. In early 1946 would come Operation Coronet, the planned invasion of the Kantō Plain, near Tokyo, on the main Japanese island of Honshu. Airbases on Kyūshū captured in Operation Olympic would allow land-based air support for Operation Coronet. If Downfall had taken place, it would have been the largest amphibious operation in history, surpassing D-Day.

The Soviet–Japanese War was a campaign of the Second World War that began with the Soviet invasion of Manchuria following the Soviet declaration of war against Japan on 8 August 1945. The Soviet Union and Mongolian People's Republic toppled the Japanese puppet states of Manchukuo in Manchuria and Mengjiang in Inner Mongolia, as well as northern Korea, Karafuto on the island of Sakhalin, and the Kuril Islands. The defeat of Japan's Kwantung Army helped bring about the Japanese surrender and the end of World War II. The Soviet entry into the war was a factor in the Japanese government's decision to surrender unconditionally, as it was made apparent that the Soviet Union was not willing to act as a third party in negotiating an end to hostilities on conditional terms.

Japan participated in World War II from 1939 to 1945 as a member of the Axis. World War II and the Second Sino-Japanese War encapsulated a significant period in the history of the Empire of Japan, marked by significant military campaigns and geopolitical maneuvers across the Asia-Pacific region. Spanning from the early 1930s to 1945, Japan employed imperialist policies and aggressive military actions, including the invasion of the Republic of China, and the Military Occupation of French Indochina.

In 1941, Japan attempted to improve relations with the United States in order to reopen trade, especially for oil, but was rebuffed. On 7 December, 1941, Japan attacked multiple American and British positions in the Pacific. The Pacific War, a major theater of World War II, further intensified Japan's engagements, leading to significant confrontations with Allied forces in the Pacific Ocean and Southeast Asia. Although initially successful, Japan took significant losses at the Battle of Midway. In addition, Japan met significant setbacks in China. On 6 and 9 August, 1945, Japan was hit by two atomic bombs, while the Soviet Union declared war and invaded Manchuria on 8 August. These events led to the surrender of Japan on 15 August.