Everyone knew in the closing days of World War II that the Soviet Union was destined to clash with the rest of the Allies. But when it attempted a blockade of West Berlin that amounted to a siege in 1948, it still took the world by surprise and threatened World War III. Luckily, President Harry S. Truman was able to call on Western air forces to resupply Berlin by air for over a year.
The Berlin Blockade, as it was known, was in reaction to Western Power attempts to re-stabilize the German economy and currency after World War II. Both the Soviet Union and the West wanted Germany to lean toward them in the post-war world because it would act as a buffer state for whichever side won.
But, beyond that, Russia wanted to ensure that Germany would never again be strong enough to invade the Soviet Union. Remember that the German military under the Kaiser had invaded Russia only 30 years before the Germans under the Fuhrer invaded the Soviet Union. The Soviets didn’t want to suffer that again.
So Soviet Premier Josef Stalin sabotaged the first attempt to overhaul the German economy, and when the Western Powers attempted to introduce the new German Deutsche Mark behind his back, Stalin instituted a total blockade of West Berlin.
Germany had been split up after the war, with America, Britain, France, and the Soviet Union all taking control of one section of the country. But each Allied power also got control of a section of Germany’s capital, Berlin, even though Berlin sat entirely within the Soviet Sector of the country.