The essential forces that fueled the Cold War— ideology, geopolitics, economics, militarization, and patriotic culture—persisted throughout the conflict. The Cold War manifested itself in waves, or cycles, of varying intensity. After the brief thaw of the mid-1950s, another intense wave of conflict emerged during the presidency of John F. Kennedy. Bitter confrontation over the anomalous western enclave in Berlin, deep inside East Germany, ended with construction of the Berlin Wall in August 1961. The wall brought a pernicious settlement to the German problem, but the concrete and barbed wire divide gave substance to Churchill's metaphor of an Iron Curtain. Despite scores of bold and often successful escapes by East Germans, the wall was an effective physical barrier, though ultimately a devastating propaganda liability and harbinger of the West's eventual triumph in the Cold War.
The 1962 Cuban missile crisis marked the apogee of Cold War confrontation, including a palpable threat of nuclear annihilation. Already livid over the loss of Cuba to communism under Fidel Castro, Americans were angered even further by Khrushchev's decision to place mediumrange nuclear warheads ninety miles off U.S. shores. From the Cuban and Soviet perspective— a perspective rarely considered under a monolithic U.S. patriotic culture—the action might have been seen as an understandable response to blatant American efforts to topple Castro, which had failed once in the Bay of Pigs invasion in April 1961 but would continue in no fewer than eight assassination plots against the Cuban leader. Moreover, as Khrushchev pointed out, nuclear missiles in Cuba would confront the United States with an analogous situation to that faced by the Soviet Union, which had nuclear weapons targeting its cities and defense sites from a variety of hostile NATO states.
Kennedy ultimately rejected the most hawkish advice he received—unilateral bombing of Cuba—but the president opted for a national television address rather than private diplomacy to demand that Khrushchev dismantle the missile sites. Kennedy then confronted the Soviets with a naval blockade, an act of war that the administration tried to soften by employing the euphemism of a "quarantine." Khrushchev backed down, but only after Kennedy renounced intervention in Cuba and pledged privately to dismantle U.S. missile sites in Turkey.
The last months of Kennedy's abortive presidency marked a turning point in the history of the Cold War. Following the crises in Berlin and Cuba, a sobered Kennedy and Khrushchev began to usher in a new thaw by establishing a "hotline" for instant communication and signing the 1963 Limited Test Ban Treaty, terminating aboveground nuclear test blasts. Cultural exchange picked up throughout the 1960s as well. Cold War rivalry continued on a global scale, but after 1963 the shadow of Armageddon began to recede, particularly as the Soviets achieved a rough parity in the nuclear arms race by the end of the decade.