The USSR had to carefully keep enough land forces in the Pacific region to deter a Japanese land invasion. (Remember that Japan controlled Manchukuo.) So, yes

The USSR had to carefully keep enough land forces in the Pacific region to deter a Japanese land invasion. (Remember that Japan controlled Manchukuo.) So, yes, the USSR had little involvement, and they had to be very careful to keep it from becoming an active front. See https://en.wikipedia.org/wiki/Battles_of_Khalkhin_Gol https://en.wikipedia.org/wiki/Battles_of_Khalkhin_Gol (that was in 1939).