Question

Why didn't the United States and its Western allies stop the construction of the Berlin Wall or the repression of the Hungarian Revolution?

Answer 1

The whole point of the Cold War was to not have another war on the scale of WW-2; especially with the use of nuclear weaponry.

Explanation:

At our remove from the Second World War, it is easy to forget just how traumatic that war was, especially as it followed one generation from the First World War. In the aftermath of the War, particularly as the Western Allies faced a truculent USSR, it was important to buy time to recover and rebuild in Europe and much of Asia.

With the emergence of the Cold War in 1945-47 as the USSR reneged on its war-time promises and imposed Stalinist Communism on Central Europe, the first priority was to avoid another major conventional war. This lead to the creation of NATO and the curbs on expanding the Korean War into Manchuria.

The emergence of the USSR as a nuclear power with its first test, and burgeoning chemical and biological warfare capabilities in the 1950s made it necessary to prevent any crisis from escalating to the point where US/NATO forces engaged Soviet/Warsaw Pact forces.

The Soviets, heirs to the Russian instinct for confrontation to test resolve as well as the ideological influences of Marxism-Leninism, had kept pushing -- which in turn led to the US policy of containment. However, for the duration of the Cold War, almost every crisis -- and every reaction to it -- had to be assessed within this context, and every risk (and opportunity) had to be carefully measured.

The Berlin Wall was the Soviet reaction to the mass-migration of people from out of Central Europe to the West. They build their barriers on their side of the border and did not provide a casus bellum. The crushing of the Hungarian Revolution of 1956 and the Prague Spring of 1968 could likewise be seen as internal matters. They were useful, however, in reminding the rest of the world about the true nature of the Soviet system.

For all the sins of Western Cold War policy -- for all the propped-up dictators, expensive arms programs. proxy wars, and policy failures, there is one overwhelming success to remember: Humanity has not had a war on the scale of WW-2 since 1945.