After world war ii in 1945, what would explain why soviet leaders wanted a buffer of satellite countries between the soviet union and germany?

After world war two, The Soviet leaders were feared from the invasion from the West and that is why they wanted a satellite of buffer countries between the Soviet Union and Germany. Stalin wanted to cover his weak western border in order to protect themselves from border penetration. 

Not sure if it’s within 12 months, but you could talk about the spreading of alt-right hate speech and whether that is covered by the right of freedom of speech? or, cover how during the midterm elections in some states many native american populations were declined to vote because they didn’t have the proper id, despite being citizens? also, the death of that journalist last month, who spoke freely and reported about the saudi government and how corrupted it is and was killed because of that (lack of free press/speech). just some ideas for this prompt, i hope at least one of them : )