Zhukov kicked the Japs’ butt in 1939, from that point on, Japan had no interest in taking on The Soviet Union.
Russia demonstrated an enormous capacity to mobilize armies
After some initial Japanese victories, the Russians amassed a much greater force
Japanese reoriented its expansionist plans from the north to the south (and, from the army to the navy)
westerners explained away the Russian victory supposing the Japanese soldier to be inferior