The main motive behind building the Berlin Wall was to stem the flow of East German citizens escaping to West Germany. During the 1950s, as the economic chasm between the two halves of Germany widened and political repression intensified in the East, growing numbers of East Germans made use of the open border to seek greater freedom in the West. Between 1948 and 1961, over 3 million East Germans had defected. It was estimated that in the first half of 1961 alone, 1,000 East Germans were crossing into West Berlin daily.
Securing the Eastern Bloc and the Soviet Union
For the Soviet Union and the Eastern Bloc, East Germany, bordering the capitalist West Germany, was a critical outpost. The East Germans leaving for the West were seen as not only a brain drain that hurt East Germany but also a potential threat to the ideological and political stability of the entire Eastern Bloc. Additionally, the West's access to East Germany offered an easy route for potential infiltration and disruption from foreign agents.
A response to the West's provocations
In addition to these concerns, the East German government's decision to construct the Wall was influenced by a series of provocations from the West, including an increase in NATO military activity in the area, the involvement of West Germany in nuclear weapons production and the support provided by the Western Allies to the East German opposition.
Ultimately, the construction of the Berlin Wall served as a drastic measure to secure and consolidate East Germany's position within the Eastern Bloc and ensure the security of the Soviet Union. It was an embodiment of the Cold War division between the capitalist West and the communist East.