After WWII the Soviet Union expanded its control over neighboring countries in Eastern Europe imposing communist puppet governments in those countries. Soviet society was at odds with Western capitalist/democratic governments and was extremely secretive in its internal operations. Much of what went on in the Soviet Union and the bordering Eastern European countries was a bit of a mystery to the West for some time. In this context, it was Winston Churchill who described the communist Eastern European (i.e. Eastern Block) countries as an Iron Curtain. The Iron Curtain was in essence the Border line between Western European Democratic governments and Eastern European communist governments.