Answer:
The Soviet Union, as part of the Cold War, wanted to support communist regimes against countries backed by the Western Coalition. They did this by providing all kinds of military, diplomatic and material support to China and North Korea.
Step-by-step explanation:
The Soviet Union and their allies, especially China, feared the arrival of Western Forces in Korea, so close to both the Soviet and Chinese border.
The aim was to keep the western forces at a distance and prevent them from building a pro-western government in Korea.
In this regard, Stalin never provided direct military support and did not want to confront the Americans in a direct war. However, they did provide air support, weapons and even took part in a couple of skirmishes. The Soviets also provided much needed medical assistance.
At the end, the Korean conflict came at a stalemate and in order to create a buffer zone, Korea was divided into North and South Korea.
The South was backed by Western governments while the North became a communist proxy.