What happened: President Harry Truman announced a new U.S. foreign policy to support countries resisting communism, beginning with aid to Greece and Turkey.

How it shows containment: It was the first major step to contain Soviet influence by giving financial and military aid to stop the spread of communism.

What happened: The U.S. gave over $12 billion in economic aid to rebuild Western Europe after WWII to prevent poverty and instability that could lead to communism.

How it shows containment: It helped stop communism by stabilizing economies and governments in Western Europe so they wouldn't turn to Soviet-style systems.

What happened: The Soviet Union blocked all land routes into West Berlin, so the U.S. and its allies flew in food and supplies to keep the city alive.

How it shows containment: The airlift stopped Soviet attempts to force West Berlin to fall under communist control and proved the U.S. would defend its allies.

What happened: NATO was formed as a military alliance between the U.S., Canada, and Western European countries to protect against Soviet aggression.

How it shows containment: NATO was a collective defense strategy to deter Soviet attacks and keep communism from spreading in Europe.