This date marks the 78th Anniversary of the Atomic Bomb over Hiroshima.

[TomWilm]

60. Japan maybe was motivated by Soviet propaganda, but ...

...Japan’s Imperial headquarters issued an emergency announcement reporting that the Soviet Union had declared war on Japan and had begun entering Manchurian territory, but added absurdly, “The scale of these attacks is not large.”
In reality, the first elements of a 1.5-million-man Soviet host, backed by small cavalry units of its ally, Outer Mongolia, were already in motion. Infantry, tank, horse cavalry, and mounted infantry, supported by river flotillas, air fleets, and 4,300 Soviet planes, would commence the invasion by striking Japanese convoys and cities in Manchuria and North Korea.
The Soviet Pacific Fleet stood ready to carry the invasion to the islands north of Japan ...
Soviet Invasion of Manchuria: Catching Japan Unawares.

... It would not be possible to fight off two great powers attacking from two different directions. The Soviet invasion invalidated the military’s decisive battle strategy, just as it invalidated the diplomatic strategy. At a single stroke, all of Japan’s options evaporated. The Soviet invasion was strategically decisive — it foreclosed both of Japan’s options — while the bombing of Hiroshima (which foreclosed neither) was not.
The Soviet declaration of war also changed the calculation of how much time was left for maneuver. Japanese intelligence was predicting that U.S. forces might not invade for months. Soviet forces, on the other hand, could be in Japan proper in as little as 10 days. The Soviet invasion made a decision on ending the war extremely time sensitive.
Japan’s leaders had reached this conclusion some months earlier. In a meeting of the Supreme Council in June 1945, they said that Soviet entry into the war “would determine the fate of the Empire.” Army Deputy Chief of Staff Kawabe said, in that same meeting, “The absolute maintenance of peace in our relations with the Soviet Union is imperative for the continuation of the war.”
The Bomb Didn’t Beat Japan … Stalin Did – Foreign Policy.