Final answer:
After WWII, Poland, Hungary, Romania, and East Germany were governed by Soviet-backed communist governments. These were one-party states that were part of a buffer zone strategy by the USSR and remained in control until the end of the Cold War.
Step-by-step explanation:
After World War II, Eastern Europe came under the influence of the Soviet Union which led to the establishment of communist governments in countries such as Poland, Hungary, Romania, and East Germany. While the initial postwar agreements, like those at Yalta and Potsdam, called for democratic elections and constitutional governance, the reality was starkly different. With the backing of the Soviet Red Army, communist parties in these states took control, setting up one-party systems that mirrored the governance of the Soviet Union. The division of Europe into Eastern and Western Europe became pronounced with the Western nations promoting capitalist democracies and the Eastern bloc falling behind what Winston Churchill dubbed the "iron curtain", referring to the Soviet influence and control over Eastern European countries. These nations—Poland, Hungary, Romania, and East Germany—experienced the installation of Soviet-backed communist regimes which were part of a broader strategy by Stalin to create a buffer zone against potential Western attacks. Despite initial elections, the communist governments in these countries lasted until the end of the Cold War, with significant reforms only beginning to emerge in the late 1980s as the Soviet Union's hold on the region waned, leading eventually to the fall of the Berlin Wall and the eventual dissolution of the Soviet Union itself.