The Cold War was a time of intense rivalry between the United States and the Soviet Union that lasted for over 40 years after World War II. During this period, the two superpowers never fought each other directly, but they competed for global influence through other conflicts, nuclear threats, and a battle of ideas. The Cold War shaped how America dealt with the world and defined the U.S.'s role as a global power.
Origins of the Cold War
The Cold War began right after World War II ended when the United States and Soviet Union—who had been allies against Nazi Germany—became rivals. These two countries had very different ideas about how governments should work and what the world should look like after the war. The creation of the United Nations in 1945 gave people hope for peace, but several things quickly caused tensions to rise:
- The Soviet Union took control of countries in Eastern Europe and set up Communist governments there, breaking promises they made at the Yalta Conference to allow free elections
- The US didn't tell Stalin about the atomic bomb they were developing during the war, which made the Soviets suspicious
- Germany was split into zones controlled by different countries, and this division started becoming permanent
- In 1946, Winston Churchill gave his famous "Iron Curtain" speech in Missouri (with President Truman sitting right there) that officially recognized the growing split between East and West
Containment Policy and Early Cold War Strategies
In 1947, President Truman created the containment policy to deal with Soviet expansion. This approach, which shaped American foreign policy for decades, focused on stopping communism from spreading to new countries rather than trying to remove it from places where it already existed.
The Truman Doctrine
In 1947, Truman asked Congress for 400 million dollars to help Greece and Turkey fight against Communist threats. In his speech, he announced what became known as the Truman Doctrine, promising American support for "free peoples" fighting against "totalitarian regimes." This speech basically declared a Cold War against the Soviet Union.
The Marshall Plan
After World War II, Europe was struggling economically, which made Communist parties more popular in many countries. Secretary of State George Marshall came up with a plan to provide massive economic aid, and in 1948 Congress approved 12 billion dollars for the European Recovery Program (Marshall Plan). This plan:
- Helped Western European countries rebuild their economies
- Stopped Communist parties from gaining power in Western Europe
- Created stronger ties between the US and the countries that received aid
The Berlin Blockade and Airlift
In 1948, Stalin blocked all roads and railways leading to the western parts of Berlin that were controlled by the US, Britain, and France. Instead of starting a military fight, Truman organized the Berlin Airlift, flying in supplies to feed and support the city. Important facts about this crisis:
- American planes flew in food, fuel, and supplies day and night
- Truman positioned B-29 bombers (which could carry atomic bombs) in England as a warning
- The Soviets finally ended the blockade in 1949, admitting defeat
NATO and Military Alliances
The North Atlantic Treaty Organization (NATO) was created in 1949 with 12 countries joining. This military alliance:
- Promised that the United States would defend Western Europe
- Stated that an attack on any member country would be treated as an attack on all of them
- Put all military forces under unified American leadership
- Protected Western Europe with America's nuclear weapons
- Eventually grew to include more countries
Cold War in Asia
The Cold War wasn't just about Europe - it quickly spread to Asia, where both superpowers tried to gain influence.
The Chinese Civil War
After World War II, China was torn apart by fighting between two groups:
- Chiang Kai-shek's Nationalists, who had America's support and money
- Mao Zedong's Communists, who were popular with many Chinese farmers
Even though America sent money and supplies to the Nationalists, their government was weakened by corruption and terrible inflation. By 1949, Mao's Communist forces had won control of mainland China, forcing Chiang and his supporters to flee to the island of Taiwan. When Mao's China formed an alliance with the Soviet Union in 1950, it completely changed the Cold War by creating a huge Communist power in Asia.
The Korean War (1950-1953)
After World War II ended, Korea was split at the 38th parallel - the Soviets controlled the North and Americans controlled the South. In June 1950, North Korean forces suddenly invaded South Korea:
- Truman quickly decided to apply his containment policy to Asia
- The UN Security Council (while the Soviet representative was boycotting meetings) approved sending military forces to help South Korea
- General Douglas MacArthur led UN forces in pushing the North Koreans back
- When UN forces got close to the Chinese border, China sent its army into the war
- MacArthur wanted to attack China directly, but Truman fired him for this and other disagreements
- The war eventually became a stalemate with neither side able to win
- In 1953, an armistice was signed that kept Korea divided near the original 38th parallel
Nuclear Arms Race and Deterrence
The invention of nuclear weapons completely changed the Cold War. Both superpowers now had weapons that could destroy each other entirely, which created a dangerous but stable situation.
Massive Retaliation
Under President Eisenhower, the United States created the hydrogen bomb in 1953, which was 1,000 times more powerful than the atomic bombs used on Japan. The Soviet Union quickly built their own hydrogen bomb. This led to a policy called massive retaliation, which meant:
- The US would respond to any Soviet attack with overwhelming nuclear force
- Both sides realized any nuclear war would destroy both countries, creating what was called "mutually assured destruction" (MAD)
- This fear of total destruction prevented the US and USSR from fighting directly, but didn't stop them from fighting smaller wars in other countries
Arms Control Efforts
After Stalin died in 1953, there were some attempts to reduce tensions:
- Eisenhower proposed his "Atoms for Peace" plan to promote peaceful uses of nuclear energy
- At the 1955 Geneva Summit, Eisenhower suggested an "Open Skies" policy that would allow each country to fly over the other to prevent surprise attacks (the Soviets said no)
- Both sides started talking about limiting their nuclear weapons
The U-2 Incident
In 1960, the Soviets shot down an American U-2 spy plane flying over their territory. This embarrassing incident:
- Forced Eisenhower to admit the US was conducting secret spy flights over Soviet territory
- Ruined a planned peace meeting in Paris
- Ended a brief period of better relations between the superpowers
Cold War Crises of the Kennedy Era
The early 1960s had several dangerous confrontations that almost led to war between the superpowers.
The Bay of Pigs Invasion
Shortly after becoming president in 1961, Kennedy approved a CIA plan to overthrow Fidel Castro's Communist government in Cuba. The plan used Cuban exiles who opposed Castro. The operation was a complete disaster:
- The 1,400 Cuban exiles who invaded were quickly captured or killed
- The Cuban people didn't rise up against Castro as the CIA had predicted
- The failed invasion actually made Castro stronger and pushed Cuba to become even closer to the Soviet Union
The Berlin Crisis
In 1961, the East German government built the Berlin Wall to stop their citizens from escaping to West Berlin. Kennedy visited Berlin and gave his famous speech where he said "Ich bin ein Berliner" ("I am a Berliner"), showing America's strong support for West Berlin and its freedom.
The Cuban Missile Crisis
The most dangerous moment of the entire Cold War happened in October 1962 when American spy planes discovered Soviet nuclear missiles being set up in Cuba, just 90 miles from Florida. Kennedy's response included:
- Setting up a naval blockade (which he called a "quarantine") around Cuba to stop more missile parts from arriving
- Demanding the Soviets remove the missiles already in Cuba
- Preparing the military for possible air strikes or invasion
For six terrifying days, the world came closer to nuclear war than ever before. Finally, Soviet leader Khrushchev agreed to remove the missiles if Kennedy promised not to invade Cuba and later removed some American missiles from Turkey. This crisis led to:
- The creation of a direct telephone "hotline" between Washington and Moscow for emergencies
- Both sides realizing how dangerous nuclear confrontation could be
- The beginning of efforts to control nuclear weapons
Détente and Later Cold War
By the 1970s, the Cold War started to change as China and the Soviet Union became enemies, creating new opportunities for American diplomacy.
Nixon's Opening to China
President Nixon and his advisor Henry Kissinger developed a policy called détente, which means a deliberate lowering of tensions. In 1972, Nixon made a surprising and historic visit to Communist China, ending decades of no contact between the countries. This smart diplomatic move:
- Started the process of normal relations with China
- Created a way to pressure the Soviets by playing the two Communist powers against each other
- Forced the Soviet Union to be more willing to discuss arms control
Strategic Arms Limitation Talks (SALT)
During his 1972 visit to Moscow, Nixon signed two important agreements with Soviet leader Leonid Brezhnev:
- SALT I put limits on anti-missile defense systems and froze the number of offensive missiles each side could have for five years
- These agreements were the first real steps toward controlling the dangerous nuclear arms race
Renewed Tensions Under Carter
At first, President Carter made progress with Soviet relations:
- He signed the SALT II treaty in 1979, though Congress never approved it
- He emphasized human rights in American foreign policy
But the Cold War heated up again when the Soviet Union invaded Afghanistan in 1979. Carter responded by:
- Announcing the Carter Doctrine, which stated that the U.S. would use military force if needed to protect its interests in the Persian Gulf region
- Imposing economic punishments, including stopping grain sales to the USSR and restricting technology exports
- Leading a boycott of the 1980 Moscow Olympics
Throughout the Cold War, American foreign policy focused on containing communism while trying to avoid a direct war that could turn nuclear. This careful balancing shaped world politics for decades and affected American life in countless ways - from military spending to domestic politics. While the Cold War would continue into the 1980s, the approaches and policies developed during this period laid the groundwork for how the conflict would eventually end peacefully.
Frequently Asked Questions
What is the Cold War and why is it called "cold"?
The Cold War was the global political, military, and ideological rivalry between the democratic, capitalist United States and the authoritarian, Communist Soviet Union from 1945 into the 1980s. U.S. policymakers pursued containment—through the Truman Doctrine, Marshall Plan, NATO, economic institutions, and military alliances—to limit Soviet influence and build a non-Communist world (CED KC-8.1.I, KC-8.1.I.A). It’s called “cold” because the two superpowers never fought each other directly in a full-scale war; instead they used proxy wars (Korean War), espionage, propaganda, economic pressure, and an arms race (hydrogen bomb, mutual deterrence) to compete. Periods swung between direct/indirect confrontations and détente. That distinction (no direct superpower battlefield clash but intense rivalry) is what makes it “cold.” For topic review tied to the AP CED and practice questions, see the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and the Unit 8 overview (https://library.fiveable.me/ap-us-history/unit-8). For extra practice, try the AP problems page (https://library.fiveable.me/practice/ap-us-history).
How did the US and Soviet Union go from allies in WWII to enemies so quickly?
They were wartime partners out of necessity, not trust. WWII united the US and USSR against Nazi Germany, but deep ideological differences—US liberal capitalism vs. Soviet communism—resurfaced once the common enemy fell. Disagreements at Yalta and Soviet control of Eastern Europe made Washington see Moscow as expansionist; George Kennan’s “containment” idea (and the Truman Doctrine/Marshall Plan in 1947) turned that fear into policy. Crisis moments sped the break: the Soviet blockade of Berlin (1948–49) and creation of NATO (1949) formalized blocs, while the Soviet atomic bomb (1949) and ensuing arms race raised stakes. That shift from alliance to cold rivalry is central to Topic 8.2 (see keywords like containment, Berlin Airlift, NATO, arms race, McCarthyism). For a compact review, check the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and practice questions (https://library.fiveable.me/practice/ap-us-history).
What's the difference between containment and rollback policies?
Containment and rollback are two different Cold War strategies. Containment (the dominant U.S. policy from 1947) aimed to stop the spread of Soviet influence and communism where it already existed—using diplomacy, economic aid (Truman Doctrine, Marshall Plan), alliances (NATO), and sometimes limited military force (Korean War). It accepts Communist regimes where they exist but tries to prevent further expansion. Rollback, by contrast, seeks to push Communist governments out and replace them with non-Communist ones—a more aggressive, often military-minded approach (some Cold War hawks pushed this idea, though containment stayed official policy). On the AP exam, expect questions tying containment to Kennan, the Truman Doctrine, Korea, and later shifts like Eisenhower’s New Look or the Domino Theory. For quick review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and practice questions (https://library.fiveable.me/practice/ap-us-history).
Why did the US get involved in the Korean War and how does it connect to Cold War tensions?
The U.S. entered the Korean War (1950–53) to uphold containment—stopping communist expansion after North Korea (backed by the USSR and later China) invaded South Korea. Truman framed intervention as consistent with the Truman Doctrine and collective-security through the UN: American forces led a UN coalition to push back North Korean forces and prevent a “domino” effect in Asia (KC-8.1.I.B.i). The war shows Cold War tensions: it was a direct military engagement rooted in rivalry with the Soviet bloc, part of the broader U.S. strategy to limit Communist military power and ideological influence, and it helped institutionalize containment (NATO-era thinking, arms buildup, and mutual deterrence). For AP prep, connect this to KC-8.1.I and practice explaining continuities/changes in Cold War policy (use the Topic 8.2 study guide on Fiveable for review: https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and try practice questions (https://library.fiveable.me/practice/ap-us-history).
Can someone explain the Marshall Plan in simple terms and why it was so important?
The Marshall Plan was a U.S. program (officially the European Recovery Program, 1948–1952) that sent about $13 billion in grants and loans to rebuild Western European economies after WWII. In simple terms: the U.S. gave money, food, and technical help so factories reopened, trade recovered, and people had jobs—making countries less likely to turn to communism. It mattered because it put containment into action economically, helped create a stable, free-market Europe, rebuilt markets for U.S. goods, and tied Western Europe to U.S. security efforts (leading toward institutions like NATO). For the AP exam, connect the Marshall Plan to containment, Truman Doctrine, and the U.S. goal of a free-market global economy (CED KC-8.1.I and KC-8.1.I.A). Want a quick review? See the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and try practice questions (https://library.fiveable.me/practice/ap-us-history).
I'm confused about NATO vs Warsaw Pact - which countries were in each and why did they form?
NATO (North Atlantic Treaty Organization) formed in 1949 as a U.S.-led collective-security alliance to contain Soviet expansion. Founding members included the U.S., Canada, Britain, France, Belgium, Netherlands, Luxembourg, Italy, Norway, Denmark, Portugal and Iceland; West Germany joined later (1955). The idea: an attack on one is an attack on all (mutual defense) to deter Soviet pressure (fits KC-8.1.I and containment). The Warsaw Pact (1955) was the Soviet response—a military alliance of the USSR and its Eastern European satellites: Soviet Union, East Germany, Poland, Czechoslovakia, Hungary, Romania, Bulgaria, and Albania (Albania later withdrew). It formalized Soviet control over allied militaries and balanced NATO’s collective-security framework. Why they formed: NATO to protect Western democracies, promote a free-market bloc, and implement containment (Truman Doctrine/Marshal Plan context). The Warsaw Pact centralized Soviet military control to secure its sphere and counter NATO. For more review, see the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and try practice questions (https://library.fiveable.me/practice/ap-us-history).
What caused the Berlin Blockade and how did the Berlin Airlift actually work?
The Berlin Blockade (June 1948–May 1949) was the Soviet response to Western moves to integrate West Germany and introduce a new currency (the Deutsche Mark). Stalin saw currency reform and steps toward a separate West German state as threats to Soviet control and to communist influence in Europe, so he cut all surface access (roads, rail, canals) to West Berlin—an attempt to force the West out without open war. The Berlin Airlift kept West Berlin alive: U.S. and British planes flew supplies into the three western sectors. Aircraft landed at tight intervals (at peak, one plane every 30 seconds), delivering food, coal, medicine, and fuel to about 2.1 million people. The operation used organized air corridors, round-the-clock flights, and carefully planned cargo loads; pilot precision and logistics overcame Soviet pressure. The blockade’s failure strengthened U.S. containment policy, helped justify NATO, and showed a Cold War pattern of indirect confrontation (see Topic 8.2 study guide: https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5). For more practice linking causes/effects for AP exam short answers and essays, try Fiveable practice problems (https://library.fiveable.me/practice/ap-us-history).
How do I write a DBQ essay about US Cold War foreign policy from 1945-1960?
Start with a one-sentence thesis that answers the prompt and sets a line of reasoning (e.g., “From 1945–1960 the U.S. moved from wartime alliance to active containment—using economic aid, collective security, and limited military force—to block Soviet influence, with continuity in anti-Communist goals but change in tactics from aid (Marshall Plan) to military action (Korea) and deterrence (nuclear arms/New Look).”). Quick plan: - Contextualize: mention postwar breakdown of the wartime alliance, onset of Cold War, and US goals (containment, free-market world, security institutions). - Document use: summarize at least 4 docs to support parts of your argument (e.g., Truman Doctrine/Marshall Plan = economic/political containment; NATO = collective security; Berlin Airlift = direct response; Korean War = military containment). - Outside evidence: bring in NSC-68, Domino Theory, McCarthyism/House Un-American Activities, Eisenhower’s New Look, Hungarian/U.S. responses, or hydrogen bomb/arms race. - Sourcing: for two documents explain POV/purpose (who wrote it and why that matters—e.g., Truman speech promotes aid; Mahan or NSC memo argues military/security needs). - Complexity: compare continuity vs. change, show how domestic politics (McCarthyism) shaped policy or how détente cycles began. Remember DBQ rules: use at least 4 documents, include 1+ outside evidence, explain POV for 2 docs, and write a clear thesis. Practice this structure with the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and more practice Qs at (https://library.fiveable.me/practice/ap-us-history).
Was the Truman Doctrine actually effective at stopping communist expansion?
Short answer: Yes—partially and conditionally. The Truman Doctrine (1947) framed U.S. containment policy: give political, military, and economic aid to resist Communist pressure (e.g., Greece and Turkey). It helped slow Soviet political influence by justifying the Marshall Plan, NATO, and long-term U.S. commitment to containing communism. But it didn’t stop all expansion—China became Communist (1949) and the Korean War (1950–53) showed containment required major military commitment. So Truman’s doctrine was effective in creating institutions and policy tools that constrained Soviet reach in Europe and the Mediterranean, but it wasn’t a cure-all; containment led to mixed results and costly engagements (Korea) and left limits in Asia. For AP exam prep, connect Truman Doctrine → containment → Marshall Plan, NATO, Korean War, and debates over direct vs. indirect confrontation (CED KC-8.1.I, KC-8.1.I.B.i). Review Topic 8.2 on Fiveable (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and practice questions (https://library.fiveable.me/practice/ap-us-history).
What were the main similarities and differences between Truman and Eisenhower's Cold War strategies?
Similar goals: both presidents wanted to contain Soviet/global Communism, build collective security (NATO), use economic aid (Marshall Plan-era logic), and compete in the arms race (hydrogen bomb, mutual deterrence). Both saw Cold War as long-term ideological struggle (continuity you should note for AP LO B). Key differences: Truman (1945–53) pursued containment through direct, conventional means—Truman Doctrine, Marshall Plan, Berlin Airlift, and the Korean War—and accepted large standing forces and emergency measures (McCarthyism era pressures). Eisenhower (1953–61) shifted toward the “New Look”: smaller conventional forces, heavier reliance on nuclear deterrence and “massive retaliation”/mutual deterrence to save costs, plus more covert action (CIA in Iran/Guatemala) and the domino theory shaping policy. Truman more willing to commit ground troops; Eisenhower preferred nuclear brinkmanship and covert influence. For the exam, practice comparing continuity/change (CED Topic 8.2)—see the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5). More unit review: https://library.fiveable.me/ap-us-history/unit-8 and extra practice: https://library.fiveable.me/practice/ap-us-history.
Why did the US support dictators in some countries if we were supposedly fighting for democracy against communism?
Short answer: the US often backed authoritarian leaders because stopping communism (containment) and protecting U.S. strategic/economic interests usually mattered more to policymakers than promoting liberal democracy everywhere. After 1945 U.S. policy (Truman Doctrine, Marshall Plan, containment) aimed to limit Soviet influence; leaders who were staunchly anti-Communist—however repressive—were seen as stabilizing allies (Domino Theory logic). Examples: covert actions in Iran (1953) and Guatemala (1954) show the priority on preventing leftist governments. This was a continuity in Cold War policy: U.S. used collective security, aid, and sometimes covert or military means to bolster non-Communist regimes even if they weren’t democratic (see KC-8.1.I and KC-8.1.I.A in the CED). On the exam, explain causes and connect to containment and specific events for context. For a focused review, check the Topic 8.2 study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and try practice questions (https://library.fiveable.me/practice/ap-us-history).
What happened during the Hungarian Revolution of 1956 and why didn't the US help them?
In October–November 1956 Hungarians rose up against Soviet control: students and workers demanded free elections, removal of Soviet troops, and reforms. Soviet forces initially pulled back, Imre Nagy became premier and announced Hungary would leave the Warsaw Pact. The USSR then sent a much larger military force in November, crushed the uprising, reinstalled a pro-Soviet government, and thousands were killed or fled. The US didn’t intervene because Hungary was inside the Soviet “sphere” of influence and direct military aid risked escalating into a wider—possibly nuclear—war. Eisenhower prioritized containment through alliances (NATO) and limited covert measures, not direct confrontation in Eastern Europe; the Suez Crisis also distracted Western attention. For AP review, link this to containment, the Hungarian Uprising (1956), and shifts between direct and indirect confrontation in the Cold War (CED KC-8.1.I, KC-8.1.I.C). For a concise Topic 8.2 study guide see Fiveable (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and practice questions (https://library.fiveable.me/practice/ap-us-history).
I don't understand how the Cold War affected everyday Americans - can someone explain McCarthyism and the Red Scare?
After WWII fear of Soviet expansion turned into domestic suspicion. The Red Scare (late 1940s–50s) meant Americans worried communists had infiltrated government, Hollywood, schools, and unions. Two big actions: HUAC (House Un-American Activities Committee) held public hearings that pressured people to name colleagues; and Senator Joseph McCarthy led McCarthyism—aggressive, often unproven accusations of Communist ties. Everyday effects: lost jobs, blacklisting (especially in entertainment), self-censorship, loyalty oaths, and chilling of protest or left-leaning politics. Courts sometimes pushed back, but many lives and careers were ruined by accusations alone. For APUSH, connect these to containment, Cold War domestic policies, and keywords (Joseph McCarthy, HUAC, McCarthyism) for short-answer or DBQ evidence. Review Topic 8.2 on Fiveable (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and practice related questions at (https://library.fiveable.me/practice/ap-us-history) to prep with examples and docs.
What were the long-term consequences of the Korean War for US foreign policy?
The Korean War made containment real: it pushed the US from words to sustained military commitments to stop Communist expansion, shaping long-term policy. Consequences included permanent overseas military presence (expanded bases and alliances like NATO), routinized collective security under the UN, bigger defense budgets, rapid development of nuclear and conventional forces (arms race/mutual deterrence), and the political use of the Domino Theory to justify interventions (leading later to Vietnam). It also strengthened presidential war-making authority in limited wars and heightened anti-Communist domestic politics (McCarthyism). For the AP exam, connect the Korean War to KC-8.1.I/B and use examples showing continuity/change in Cold War policy (containment, collective security, arms race). Review Topic 8.2 for concise CED-aligned points (study guide: https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and practice with AP-style questions (https://library.fiveable.me/practice/ap-us-history).
How did the launch of Sputnik change the Cold War and why was it such a big deal?
Sputnik’s 1957 launch shifted the Cold War from political/ military competition to a visible tech/ideological race. It proved the USSR could deliver satellites (and potentially long-range missiles), sparking U.S. fear about missile gaps and Soviet technological advantage. Immediate effects: bigger defense and science budgets, creation of NASA, the National Defense Education Act (boosting STEM), and intensified arms-race logic (hydrogen bomb/ICBM development and mutual deterrence). Politically it pushed U.S. leaders to treat science/education as national security priorities and hardened Cold War competition—accelerating space and missile programs and shaping containment into high-tech rivalry. On the AP exam, use Sputnik as evidence of change in Cold War policy (increased spending, new institutions, arms race escalation) for short answers or DBQs about continuity/change (Topic 8.2). Review this topic in Fiveable’s study guide (https://library.fiveable.me/ap-us-history/unit-8/cold-war-1945-1980/study-guide/vLoggG1eZuSCQnMwTaE5) and try practice questions (https://library.fiveable.me/practice/ap-us-history).