The Soviet Union established satellite states in Eastern Europe because it wanted

To secure its territory

Explanation:

After the World war II the soviet union remained the only country in Eastern Europe still practicing the communist system of Governance. The leader of the soviet union Stalin felt that the Western part of Europe and America who were strongly against its communist system of Governance might attack/invade them so The Soviet Union established soviet satellite states in Eastern Europe in order to checkmate any kind of Invasion.

The Soviet Union was the only communist country left in the world after the war was over. Th soviet union wanted to as well control Eastern Europe and protect its Borders.

Answer: protection against another invasion