Answer:
Stalin cut off supply lines to democratic West Berlin.
Explanation:
All of Berlin was in Soviet Union occupation zone as declared at end of WWII.
However  West Berlin was split between USSR having East Berlin and British/American and French having half of the capital like half of Germany itself was split up.
Stalin cut off all land transportation routes into the Allied zone. Â Fortunately Allied/American air transport kept West Berlin supplied with necessities of food, fuel, medicine etc. Â Until Stalin had to give up his Cold War attempt to capture all of Berlin without armed conflict.
