In the 1950s and 1960s, the USSR controlled Eastern European nations via a number of methods, including
A
establishing puppet governments and using force to crush any dissent or opposition to communist rule.B
establishing a blockade along the Iron Curtain and preventing anyone from entering or leaving those countries.C
preventing those countries from joining the United Nations and creating a policy of containment.D
encouraging opponents to leave those countries and establishing refugee organizations in Western Europe.