At the end of World War II, the Soviet Union was in control of Poland, Czechoslovakia, and other countries in Eastern Europe. In the Long Telegram, George Kennan urged the policy of containment of Soviet power. The policy was adopted by Truman, who implemented the Truman Doctrine to support countries under threat of communist aggression.

In the United States, fear of the spread of communism led to the establishment of a Loyalty Program in which federal employees were investigated for communist sympathies. The House Un-American Activities Committee investigated communist infiltration of Hollywood, and Wisconsin Senator Joseph McCarthy claimed to know the identity of dozens of communists in the State Department.

In this atmosphere, when communist North Korea invaded South Korea in 1950, starting the Korean War, the United States led a UN force to support South Korea. As General Douglas MacArthur pushed toward the Yalu River, the Chinese invaded and drove the US forces back. MacArthur and Truman disagreed about whether to use nuclear weapons against China, and Truman fired the General. The war dragged on until 1953, when an armistice was signed, dividing the Korean Peninsula.

President Eisenhower and his Secretary of State John Foster Dulles created the New Look policy. The New Look was a military strategy of expanding the US nuclear arsenal and using the threat of nuclear war to accomplish US goals. Covert operations by the CIA to destabilize communist regimes were also part of the New Look strategy. For instance, in 1954, the CIA helped overthrow Guatemala’s left-leaning president Jacobo Arbenz.

President Kennedy pushed back against the Communist takeover of Cuba, backing the disastrous Bay of Pigs invasion and placing Cuba under sanctions. He held firm when the USSR placed nuclear missiles in Cuba during the Cuban Missile Crisis. Kennedy’s Alliance for Progress funneled millions into Latin America to try to stabilize Latin America and create a climate in which Marxism would be less attractive. The effort was ultimately unsuccessful, however.

As the French fought the comminst forces of Hồ Chí Minh, seeking to maintain control of Vietnam, the United States provided financial assistance; eventually, the US was providing about 80% of the funding for the French war effort. Under President Johnson, the war escalated, following the 1964 Gulf of Tonkin Incidents. Some Canadians enlisted with the US to fight in Vietnam, but other Canadians harbored US draft dodgers. In Latin America, there were protests against the war, for example in Mexico and Costa Rica.

As President, Richard Nixon pursued two very different strategies with regard to the Cold War. On the one hand, he campaigned on a promise to end the war in Vietnam, implemented Vietnamization and withdrew its last US troops from Vietnam in 1973. And, Nixon pursued the policy of relaxing tensions with the USSR called détente; he reached out to the USSR, signed the SALT I agreement, which placed limits on strategic arms, and met with Leonid Brezhnev in 1972. However, Nixon also used the CIA to help overthrow Chile’s socialist government led by Salvador Allende. President Ford continued the policy of détente during his short time in office.

Jimmy Carter became president for a single term, starting in 1977. He wanted to focus on the US economy, the environment, and human rights rather than on the Cold War. Carter withdrew funding from governments in Latin America that were known for their abuse of human rights. The Panama Canal Zone had been leased in perpetuity by the US from Panama, but Carter argued that the US should return the land to Panama and signed a treaty promising to do so; the canal was handed over to Panama in 1999. Carter was criticized for this, as well as for his handling of the Iranian hostage crisis.

Canada’s role in the Cold War began with the Gouzenko Affair in which a Soviet spy, Igor Gouzenko, defected and revealed the existence of a vast Soviet spy network that stretched from Canada to the UK, penetrating many parts of the government. As in the United States, fear of the expansion of communism increased, peaking in the 1950s. Canada became a member of NATO and joined the US in the Korean War. They also joined NORAD and allowed early-warning radar installations to be placed in Canada to provide warning of a Soviet attack. However, Canadians were reluctant to let the United States place nuclear weapons in Canada, and the presence of nuclear weapons on Canadian soil from 1963 to 1972 was very controversial. Canada also maintained neutrality during the Vietnam War.