Why did the United States and the Soviet Union become bitter rivals after working together to win World War II?
Analyze the origins of the Cold War, including the rivalry between the United States and the Soviet Union, the policy of containment, the Truman Doctrine, the Marshall Plan, and the division of Europe (Louisiana Student Standards for Social Studies, US History Standard 5: Cold War Era).
A LEAP-level answer on the origins of the Cold War for the Louisiana US History test: the rivalry between democracy and communism, the policy of containment, the Truman Doctrine and the Marshall Plan, the Iron Curtain and the division of Europe, NATO, and the Berlin blockade, with worked source questions.
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What this topic is asking
The wartime alliance between the United States and the Soviet Union collapsed almost as soon as the war ended, opening a forty-year global rivalry. Standard 5 (Cold War Era) wants you to analyze the origins of the Cold War, the clash between democracy and communism, and the American response: the policy of containment, the Truman Doctrine, the Marshall Plan, and the division of Europe. LEAP often uses a Cold War cartoon, a map of divided Europe, or a policy excerpt as the source.
Why the alliance broke down
The United States and the Soviet Union had fought together against Hitler, but they were deeply opposed in ideology and interests.
After the war, the Soviet Union kept its armies in Eastern Europe and installed communist governments there, seeking a buffer of friendly states. The United States saw this as aggressive expansion. Mutual distrust, sharpened by the atomic bomb, turned former allies into rivals.
The Iron Curtain and containment
As Soviet control hardened over Eastern Europe, the continent split in two.
Winston Churchill warned that an "Iron Curtain" had descended across Europe, dividing the Soviet-dominated communist East from the free West. The American response was the policy of containment: rather than trying to destroy communism where it existed, the United States would work to stop it from spreading to new countries. Containment became the guiding strategy of American foreign policy for the entire Cold War.
The tools of containment
The Berlin crisis
Germany, and its capital Berlin, sat at the front line. Both Germany and Berlin had been divided into Soviet and Western zones. In 1948 the Soviets blockaded West Berlin, cutting off land routes to starve it into submission. Rather than abandon the city or risk war, the United States and its allies organized the Berlin Airlift, flying in food and fuel for nearly a year until the Soviets lifted the blockade. The crisis showed both sides' determination and became an early symbol of Cold War confrontation.
Exam-style practice questions
Practice questions written in the style of LDOE exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
LA LEAP 2025 US History (style)1 marksA source describes American aid in 1947 to help rebuild the economies of war-torn Western Europe and resist the spread of communism. This program was theShow worked answer →
A single-select item assessing analysis of a source (Standard 5; Standard 1 source analysis).
Correct answer: the Marshall Plan, which gave billions in aid to rebuild Western Europe.
The Marshall Plan was a key tool of containment, reasoning that prosperous, stable nations would resist communism. Distractors such as "the Truman Doctrine" describe the related pledge to aid nations resisting communism but not the European recovery program itself, and "Lend-Lease" was a World War II policy.
LA LEAP 2025 US History (style)2 marksPart A: What was the American policy of containment? Part B: How did the Truman Doctrine put containment into practice?Show worked answer →
A two-part evidence-based item (Standard 5; Standard 1 claims and evidence).
Part A (1 point): containment was the policy of stopping the spread of communism, keeping it contained within the countries where it already existed rather than letting it expand.
Part B (1 point): the Truman Doctrine put containment into practice by pledging American aid (initially to Greece and Turkey) to any nation resisting communist takeover, committing the United States to support free peoples against communism worldwide. A distractor saying the Truman Doctrine sought to spread communism reverses its purpose.
Markers reward defining containment in Part A and linking the Truman Doctrine's aid pledge to it in Part B.
Related dot points
- Analyze the major conflicts and domestic effects of the Cold War, including the Korean War, the arms race and the space race, the Cuban Missile Crisis, and the second Red Scare and McCarthyism (Louisiana Student Standards for Social Studies, US History Standard 5: Cold War Era).
A LEAP-level answer on Cold War conflicts for the Louisiana US History test: the Korean War, the nuclear arms race and the space race, the Cuban Missile Crisis, and the second Red Scare and McCarthyism at home, with worked source questions.
- Analyze the goals, strategies, and achievements of the civil rights movement, including Brown v. Board of Education, nonviolent protest, key leaders and events, and the landmark civil rights laws (Louisiana Student Standards for Social Studies, US History Standard 5: Cold War Era).
A LEAP-level answer on the civil rights movement for the Louisiana US History test: Brown v. Board of Education, the Montgomery Bus Boycott, Martin Luther King Jr. and nonviolent protest, the March on Washington, and the Civil Rights Act of 1964 and Voting Rights Act of 1965, with worked source questions.
- Analyze the Vietnam War and its effects on American society, including the policy of containment in Asia, escalation, the antiwar movement, and the war's legacy (Louisiana Student Standards for Social Studies, US History Standard 5: Cold War Era).
A LEAP-level answer on the Vietnam War for the Louisiana US History test: the domino theory and containment in Asia, the Gulf of Tonkin and escalation, the Tet Offensive, the antiwar movement and the credibility gap, the end of the war, and the War Powers Act, with worked source questions.
- Analyze the wave of social change in the 1960s and 1970s, including the Great Society, the women's movement, other rights movements, the counterculture, and the expansion of rights through landmark legislation and Supreme Court decisions (Louisiana Student Standards for Social Studies, US History Standard 5: Cold War Era).
A LEAP-level answer on the social change of the 1960s and 1970s for the Louisiana US History test: Johnson's Great Society and the war on poverty, the women's movement and the ERA, other rights movements, the counterculture, the environmental movement, and the Warren Court, with worked source questions.
- Analyze the Holocaust and the decision to use the atomic bomb, including the genocide carried out by Nazi Germany, the American response, the development of the bomb, and the debate over its use (Louisiana Student Standards for Social Studies, US History Standard 4: Becoming a World Power through World War II).
A LEAP-level answer on the Holocaust and the atomic bomb for the Louisiana US History test: the Nazi genocide of six million Jews and millions of others, liberation and the response, the Manhattan Project, the bombings of Hiroshima and Nagasaki, and the debate over the decision to use the bomb, with worked source questions.
Sources & how we know this
- 2025-2026 Assessment Guide for US History (LEAP 2025) — Louisiana Department of Education (2025)
- K-12 Louisiana Student Standards for Social Studies — Louisiana Department of Education (2022)