What did USSR do in 1948 which was aggressive and what actions did us take in response?

The Soviets/Russians closed off West Berlin, located in East Germany, to land vehicles (cars, trucks and railroads) from West Germany. The Russians closed off West Berlin to try and show how strong and powerful they were. The USA response was to fly airplanes around the clock, non stop, into West Berlin and it was called the Berlin Airlift. It lasted for several months, a few planes crashed, due to accidents, (none were fired upon by the Communists), and some aircrews died or were badly injured. After seeing that the airlift made the land blockade a failure, the Soviets/Russians gave up and opened up West Berlin to land traffic.