From the perspective of the strategic defense policy of the Soviet Union after the Second World, the so-called »Sovietization of Eastern and Central Europe« was an entirely logical consequence of geopolitics. The Soviet Union had been attacked by the largest invasion in human history which began the Second World War on the Eastern Front, as the Central European power of Nazi Germany invaded Soviet territory. The formation of what the Western powers termed the »Western Bloc« was a direct result of, on the one hand, the Soviet defeat of the invaders, and, on the other hand, filling the power vacuum that now existed in Eastern and Central Europe. The geopolitical chessboard after the Second World War meant that there were now two superpowers in the world: the Soviet Union and the United States.
If the Soviet Union had conceded geopolitical influence in Central and Eastern Europe, these countries would have been “Americanized” instead of “Sovietized”, much like Western Europe was Americanized after the Second World War period. Furthermore, after the collapse of the Soviet Union, the Americans continued to expand the membership of NATO countries ever eastward, in direct violation of an agreement with Mikhail Gorbachev after the collapse of the USSR, thereby indicating that if Stalin had also decided to relinquish influence in the areas where Nazi Germany had been defeated the Americans would have moved into this geopolitical space, causing further defense problems for the Soviet Union.
In this regard, the decision to form the “Eastern Bloc”, explicitly and officially formulated along shared ideological lines, i.e., communism, as well as creating a military alliance in the form of the Warsaw Pact which served as a counter balance to the American-led NATO can only be viewed as an example of sound strategic thinking. Whereas the Cold War conflict was conditioned by a certain ideological warfare between the Soviet idea of communism and the American idea of capitalism, there were also geopolitical issues in Europe which further emphasize the soundness of this decision. For example, influential geopolitical thinkers such as the Englishman Harold MacKinder posited the importance of the Eurasian land space as the key to world domination. This landmass fell largely within the boundaries of the historical Soviet Union: MacKinder posited that controlling Central and Eastern Europe were crucial to controlling all of Eurasia.
Hitler and the Nazis, influenced by their own school of geopolitics, also recognized the importance of Central and Eastern Europe and the control of the Western half of Eurasia, arguably partly instigating the Nazi decision to go to war. In this context, after the Second World War ended, this of course does not mean the end of strategic geopolitics: it merely meant that the Soviet Union was now faced with a new geopolitical opponent, that of the United States. Influential geopolitical thinkers for the U.S., such as Zbigniew Brzezinski have advocated cutting off the Soviet Union and now Russia from Central and Eastern Europe, as a way to ensure U.S. hegemony over the world. In so far as these geopolitical lines have not changed, it would have been strategic suicide for the Soviet Union not to claim in their immediate sphere of influence Central and Eastern Europe, as this would have left the country open to American aggression in a key geopolitical area.
Hence, from the perspective of strategy, geopolitics, realpolitik and the realism of International Relations, the Soviet decision was entirely justified, as if they had not prosecuted this act, the Americans would have led their own “Americanization” of the region, a phenomenon that is currently the geopolitical reality of Central and Eastern Europe through means such as NATO.