why did the USSR blockade western access to berlin in the winter of 1948? how did the allies break it?

Answer 1

They were trying to starve out the western portion of Berlin so they could take control of it. The treaty specifically allowed the western powers air access through a narrow corridor, so the western nations flew in supplies for a long time to keep the city from falling to the Communists. It was the largest airlift operation in history and likely would never have been attempted 10 years later.

Answer 2

The Soviets were trying to possess all of Berlin (the Allies occupied the Western part only and Berlin was completely surrounded by East Germany).

The Allies broke it by a large-scale airlift of all kinds of supplies needed to keep on going, and so they did.

Answer 3

U.S./ Allied powers controlled half of berlin and released it to the berlin government to be ran as they saw fit. The other half was Soviet occcupied and they wanted communist rule.
The blockade was their attempt to stop western government from settling into Western germany and western berlin. U.S. did not break in, but merely airlifted goods andaid the west berliners during that year until the blockade was lifted.
Neither side made it a military thing, so it remained peaceful.
It is was of the first issues of the cold war.

Answer 4

This is from the Truman library:
http://www.trumanlibrary.org/whistlestop/study_collections/berlin_airlift/large/docs.php