The Soviet Union wanted to gain access to build bases on warm-water ports (ports that do not freeze over in the winter) for easy access to the ocean.
The Soviet Union wanted to gain new territory for expansion of communism throughout the world.
The Soviet Union desired to increase its influence by surrounding itself with satellite nations that could prove beneficial for military and economic gain.
Explanation:
The Soviet Union had a lot of land mass that bordered the Arctic ocean and other areas in the Soviet Union were quite cold as well which led the Soviets to desire a warm water port that they could use to access the ocean more effectively.
The also wanted to spread communism around the world and so desired territory to do so.
Finally, the Soviet Union wanted to increase its influence so it surrounded itself with Satellite states such as those in the Warsaw Pact and Soviets in the Soviet Union.
