Allies Become Enemies
The United States and the Soviet Union were allies during World War II. In February 1945, they
agreed to divide Germany into separate zones. Each zone was occupied by the soldiers of one of the Allies.
The Allies also helped form the United Nations (UN) in 1945. The UN pledged to prevent war.
The United States and the Soviet Union had important differences after the war. The United States
suffered few casualties and was the richest nation in the world. The Soviet Union suffered enormous loss of life
and damage to its cities.
There were also striking political differences. The United States wanted to create new markets
for its goods. It also wanted to encourage democracy. The Soviet Union wanted to set up Communist governments
and make sure it did not get attacked again from the west. These differences caused tensions between the two
How did U.S. goals and Soviet goals differ after World War II?
Eastern Europe's Iron Curtain
At the end of World War II, Soviet forces occupied lands along its western border. After the war, Stalin
made sure Communist governments were in place in these lands: Albania, Bulgaria, Hungary, Czechoslovakia, Romania,
Poland, and Yugoslavia. This divided Europe between East and West. Winston Churchill called this division the
What countries were separated from the West by the iron curtain?
United States Tries to Contain Soviets
Truman began a policy of containment - blocking the Soviets from spreading communism. Under the Truman
Doctrine, the United States helped nations that were threatened by communism. The United States also adopted the
Marshall Plan in 1947. This plan gave food and other aid to European countries to help them recover from the war.
In 1948, the Soviets and Americans clashed over Germany. France, Britain, and the United States agreed to
pull their troops out of Germany. They let the three zones that they occupied unite. But the Soviets refused to leave their
zone. Then they cut off all highway and train traffic into Berlin, which was deep within the Soviet zone. The United States
and Britain responded with the Berlin airlift. They flew food and supplies into the city for 11 months. Finally, the Soviets
lifted the blockade.
How did the United States respond to communism?
Cold War Divides the World
Why did tensions between superpowers increase?
The struggle between the United States and the Soviet Union was called the Cold War. Many countries supported
one superpower or the other.
The United States, Canada, and several countries in Western Europe formed the North Atlantic Treaty Organization (NATO).
NATO was a military alliance. Each nation promised to defend any other member that was attacked. The Soviets and the countries of Eastern
Europe made a similar agreement. It was called the Warsaw Pact.
In 1949, the Soviet Union announced that it
had developed an atomic bomb. Three years later,
both superpowers had an even more deadly
weapon—the hydrogen bomb. Soon both nations
were involved in an arms race. They produced
more and more nuclear weapons and developed
new ways to deliver them. Both sides were willing
to go to the brink, or edge, of war. This became
known as brinkmanship.
In 1957, the Soviet Union launched Sputnik,
the world's first human-made satellite. Many people were shocked. Americans felt that the Soviets
were far ahead in science and technology. The
United States then began spending huge amounts
of money to improve science education.
What developments or events increased tensions during the Cold War?