Answer:
The Berlin Airlift broke the backs of the Soviets, so to speak, by proving that there was a point at which they would stand down.
The Berlin Airlift was the result of the Berlin Blockade. The Soviets wanted all of Berlin for themselves, and you can understand why: Berlin became a free, extremely prosperous city while it was surrounded by communists. Communists cannot have something like Berlin where its people can see it. So...the Sovs kept rail, road and water traffic from entering Berlin because Berlin has to be supplied from the outside (there is farmland in Berlin but not nearly enough to feed a couple million people) and there was, in the Soviets' view, no way the city could be supplied by air.
Wrong. The city WAS supplied by air--the operation was completely uneconomic, but that's not the point. When the Soviets ended the Blockade, they became far weaker because they proved there were limits to their might.