To stop the British, French and the USA from gaining goods.
To counter militarily and economically NATO
Relations were made a lot worse as Berlin was more obviously divided. There were increased tensions between Russia and America because Stalin didn't want to allow the East and the West to join together and was trying to stop that. When the Berlin Airlift happened. it made Communism look bad which Stalin didn't like.
Stalin put the Berlin Blockade in place on the 24th of June 1948. The blockades aim from the Soviet point of view was to force all "Westerners" (that is Berliners) out of Eastern Berlin which was the Soviet occupation zone. However, Truman the American president decided to airlift supplies into Eastern Berin and the blockade was lifted by Stalin a year later. The outcome was widespread German resentment against the Communists and support for the Americans
That would be the North Atlantic Treaty Organization, or NATO.
NATO's main purpose was to offer an alliance for the countries of western Europe, basically to stop the spread of communism by defending any country within the treaty that was in need of defense.
West Berlin was in the middle of East Germany, and was surrounded on all sides by it. That's what the famous Berlin Airlift was about- the Soviets disallowed the Western Allies from going into Berlin by land, so the Allies had to use airplane to send supplies into West Berlin.
The effort to supply Berlin through the Soviet Blockade. (apex)
because Berlin was the only place where America and England had control of in the east part of Russia during the cold war, so stop other countries turning into communism, they put a lot of money into west Berlin, to persuade people that life is better without communism.
To stop the spread of Communism
I think you mean the Berlin Wall, which was built in 1961 to stop people living in East Berlin fleeing to the West.As communism began to fall apart people wanted the wall taken down.This finally happened on 9 November 1989 .
President Truman started sending planes filled with supplies in the summer of 1948.Planes flew none stop to the for almost a year sending Berlin food and water as well as supplies during the cold winters. The Berlin Airlift made more than 200,000 flights for eleven months until the Soviets lifted the blockade on Berlin in May of 1949.