https://www.milsurps.com/images/impo...Japflags-1.jpg
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The Russians finally declared war against Japan in the very latter stages of the war to justify their seizure of land..
Additionally, in 1938-1939, the Japanese attacked the Ivans on the Manchurian-Mongolian border. The Japanese got their a$$es whipped, and only the intervention of the US and the Germans kept the major border clash from escalating into a full-blown war. The photo could also, quite likely, have been from that earlier conflict.
FWIW, the Soviet Commander that beat the Japanese so convincingly was none other than Georgy Zhukov!