Answer:
protect itself from invasion
Explanation:
The USSR led by J Stalin created satellite states as a barrier to invasion from Eastern Europe. The security policy after WWII went for establishing and controling this states.
From 1945 to 1949 Stalin proactively sought an extension of Soviet influence in East Europe, the countries included East Germany, Czechoslovakia,Bulgaria,Romania,Poland,etc.
The communists goverments was set in all these countries and they remained subject to Soviet foreign policy later creating the Warsaw Pact- a military alliance for the socialist world.
