Why didn't the Japanese invade the Russians in WW2?

https://www.quora.com/Why-didnt-the-Japanese-invade-the-Russians-in-WW2/answer/%E6%A1%91%E7%94%B0-%E5%81%A5%E5%8F%B8-Kuwata-Kenji?prompt_topic_bio=1

Russia was not a colony of Western countries.