Cuban Missile Crisis

In late 1961, Fidel Castro asked for more SA-2 anti-aircraft missiles from the Soviet Union. The request was not acted upon by the Soviet leadership. In the interval, Castro began criticizing the Soviets for lack of "revolutionary boldness", and began talking to China about agreements for economic assistance. In March 1962, Castro ordered the ousting of Anibal Escalante and his pro-Moscow comrades from Cuba's Integrated Revolutionary Organizations. This affair alarmed the Soviet leadership and raised fears of a possible US invasion. As a result, the Soviet Union sent more SA-2 anti-aircraft missiles in April, as well as a regiment of regular Soviet troops.

Historian Timothy Naftali writes that Escalante's dismissal was a motivating factor behind the Soviet decision to place nuclear missiles in Cuba in 1962. According to Naftali, Soviet foreign policy planners were concerned that Castro's break with Escalante foreshadowed a Cuban drift toward China, and they sought to solidify the Soviet-Cuban relationship through the missile basing program.

The Cuban government regarded US imperialism as the primary explanation for the island's structural weaknesses. The US government had provided weapons, money, and its authority to the military dictatorship of Fulgencio Batista that ruled Cuba until 1958. The majority of the Cuban population were tired of the severe socioeconomic problems associated with the US domination of the country. The Cuban government was thus aware of the necessity of ending the turmoil and incongruities of US-dominated prerevolution Cuban society. It determined that the US government's demands, part of their hostile reaction to Cuban government policy, were unacceptable.

With the end of World War II and the start of the Cold War, the US government sought to promote private enterprise as an instrument for advancing US strategic interests in the developing world. It had grown concerned about the expansion of communism.

In December 1959, under the Eisenhower administration and less than twelve months after the Cuban Revolution, the Central Intelligence Agency (CIA) developed a plan for paramilitary action against Cuba. The CIA recruited operatives on the island to carry out terrorism and sabotage, kill civilians, and cause economic damage. At the initiative of the CIA Deputy Director for Plans, Richard Bissell, and approved by the new President John F. Kennedy, the US launched the attempted Bay of Pigs Invasion in April 1961 using CIA-trained forces of Cuban expatriates. The complete failure of the invasion, and the exposure of the US government's role before the operation began, was a source of diplomatic embarrassment for the Kennedy administration. Former President Eisenhower told Kennedy that "the failure of the Bay of Pigs will embolden the Soviets to do something that they would otherwise not do."

Following the failed invasion, the US massively escalated its sponsorship of terrorism against Cuba. Starting in late 1961, using the military and the CIA, the US government engaged in an extensive campaign of terrorism against civilian and military targets on the island. The terrorist attacks killed significant numbers of civilians. The US armed, trained, funded and directed the terrorists, most of whom were Cuban expatriates. Terrorist attacks were planned at the direction, and with the participation, of US government employees and launched from US territory. The attacks would continue through 1965. In January 1962, US Air Force General Edward Lansdale described the plans to overthrow the Cuban government in a top-secret report, addressed to Kennedy and officials involved with Operation Mongoose. CIA agents or "pathfinders" from the Special Activities Division were to be infiltrated into Cuba to carry out sabotage and organization, including radio broadcasts. In February 1962, the US launched an embargo against Cuba, and Lansdale presented a 26-page, top-secret timetable for implementation of the overthrow of the Cuban government, mandating guerrilla operations to begin in August and September. "Open revolt and overthrow of the Communist regime" was hoped by the planners to occur in the first two weeks of October.

The terrorism campaign and the threat of invasion were crucial factors in the Soviet decision to place nuclear missiles on Cuba, and in the Cuban government's decision to accept. The US government was aware at the time, as reported to the president in a National Intelligence Estimate, that the invasion threat was a key reason for the increased Soviet military presence.

When Kennedy ran for president in 1960, one of his key election issues was an alleged "missile gap" with the Soviets. In fact the US at that time was ahead of the Soviets and by an increasingly wide margin. In 1961 the Soviets had four R-7 Semyorka intercontinental ballistic missiles (ICBMs); by October 1962, some intelligence estimates indicated a figure of 75.

The US had 170 ICBMs and was quickly building more. It also had eight George Washington- and Ethan Allen-class ballistic missile submarines, with the capability to launch 16 Polaris missiles, each with a range of 2,500 nautical miles (4,600 km). The Soviet First Secretary, Nikita Khrushchev, increased the perception of a 'missile gap' when he boasted to the world that the Soviets were building missiles "like sausages", but Soviet missile numbers and capabilities were nowhere close to his assertions. The Soviet Union had medium-range ballistic missiles in quantity, about 700, but they were unreliable and inaccurate. The US had a considerable advantage in total number of nuclear warheads (27,000 against 3,600) and in the technology required for accurate delivery. The US also led in missile defensive capabilities, naval and air power. The Soviets had a two-to-one advantage in conventional ground forces, particularly in field guns and tanks in the European theatre.

Khrushchev also thought Kennedy was weak. This impression was confirmed by the President's response during the Berlin Crisis of 1961, particularly to the building of the Berlin Wall by East Germany to prevent its citizens from emigrating to the West. The half-hearted nature of the Bay of Pigs invasion reinforced his impression that Kennedy was indecisive and, as one Soviet aide wrote, "too young, intellectual, not prepared well for decision making in crisis situations... too intelligent and too weak". Speaking to Soviet officials in the aftermath of the crisis, Khrushchev said, "I know for certain that Kennedy doesn't have a strong background, nor, generally speaking, does he have the courage to stand up to a serious challenge." He told his son Sergei that on Cuba, Kennedy "would make a fuss, make more of a fuss, and then agree".

In May 1962, Soviet First Secretary Nikita Khrushchev decided to counter the growing lead of the US in developing and deploying strategic missiles by placing Soviet intermediate-range nuclear missiles in Cuba, despite the misgivings of the Soviet Ambassador in Havana, Alexandr Ivanovich Alexeyev, who argued that Castro would not accept them. Khrushchev faced a strategic situation in which the US was perceived to have a "splendid first strike" capability that put the Soviet Union at a disadvantage. In 1962, the Soviets had only 20 ICBMs capable of delivering nuclear warheads to the US from inside the Soviet Union. Their poor accuracy and reliability raised serious doubts about their effectiveness. A newer, more reliable generation of Soviet ICBMs only became operational after 1965.

Soviet nuclear capability in 1962 placed less emphasis on ICBMs than on medium and intermediate-range ballistic missiles (MRBMs and IRBMs) which could strike American allies and most of Alaska from Soviet territory, but not the contiguous United States. As Graham Allison, the director of Harvard University's Belfer Center for Science and International Affairs, pointed out, "The Soviet Union could not right the nuclear imbalance by deploying new ICBMs on its own soil. In order to meet the threat it faced in 1962, 1963, and 1964, it had very few options. Moving existing nuclear weapons to locations from which they could reach American targets was one."

A second reason that Soviet missiles were deployed to Cuba was that Khrushchev wanted to bring West Berlin, which was controlled by the American, British and French within Communist East Germany, into the Soviet orbit. The East Germans and Soviets considered western control over a portion of Berlin to be a threat to East Germany. Khrushchev made West Berlin the central battlefield of the Cold War. He believed that if the US did nothing over the deployments of missiles in Cuba, he could force the West out of Berlin by using the missiles as a deterrent to western countermeasures in Berlin. If the US tried to bargain with the Soviets after it became aware of them, Khrushchev could demand a trade of the missiles for West Berlin. Since Berlin was strategically more important than Cuba, the trade would be a win for Khrushchev, as Kennedy recognized: "The advantage is, from Khrushchev's point of view, he takes a great chance but there are quite some rewards to it."

Thirdly, it seemed from the perspective both of the Soviet Union and of Cuba that the United States wanted to invade Cuba or increase its presence there. In view of actions which included an attempt to expel Cuba from the Organization of American States, a campaign of violent terrorist attacks on civilians which the US was carrying out on Cuba, economic sanctions against the country and an earlier attempt to invade the island, Cuban officials understood that America was trying to overrun their country. The USSR would respond by placing missiles on Cuba, which would secure the country against attack and keep it in the Socialist Bloc.

American missiles could have been launched from Turkey to attack the USSR before the Soviets had a chance to react. Placing nuclear missiles on Cuba would have created a balance of mutual assured destruction. If the United States launched a nuclear strike against the Soviet Union, the Soviets would have been able to react by launching a retaliatory nuclear strike against the US.

Placing nuclear missiles on Cuba was also a way for the USSR to show support for Cuba and the Cuban people who viewed the United States as a threat. The USSR had become Cuba's ally after the Cuban Revolution of 1959. According to Khrushchev, the Soviet Union's motives were "aimed at allowing Cuba to live peacefully and develop as its people desire".

Arthur M. Schlesinger Jr., a historian and adviser to Kennedy, told National Public Radio in an interview on 16 October 2002 that Castro did not want the missiles, but Khrushchev pressured him to accept them. Castro was not completely happy with the idea, but the Cuban National Directorate of the Revolution accepted them, both to protect Cuba against US attack and to aid the Soviet Union.

In early 1962, a group of Soviet military and missile construction specialists accompanied an agricultural delegation to Havana and met Cuban prime minister Fidel Castro. According to one report, the Cuban leadership expected that the US would invade Cuba again and enthusiastically approved the idea of installing nuclear missiles on Cuba. According to another source, Castro objected to being made to look like a Soviet puppet, but was persuaded that missiles in Cuba would be an irritant to the US and would help the interests of the entire socialist camp. The deployment would include short-range tactical weapons with a range of 40 km, usable only against naval vessels, that would provide a "nuclear umbrella" for attacks upon the island.

By May, Khrushchev and Castro agreed to place strategic nuclear missiles secretly in Cuba. Like Castro, Khrushchev felt that a US invasion of Cuba was imminent and that to lose Cuba would do great harm to the communists, especially in Latin America. He said he wanted to confront the Americans "with more than words.... the logical answer was missiles". The Soviets maintained their tight secrecy, writing their plans in longhand, which were approved by Marshal of the Soviet Union Rodion Malinovsky on 4 July and Khrushchev on 7 July as Operation Anadyr.

Operation Anadyr entailed elaborate denial and deception, known as "maskirovka". All the planning and preparation for transporting and deploying the missiles was carried out in the utmost secrecy, with only a very few knowing the exact nature of the mission. Even the troops detailed for the mission were given misdirection by being told that they were headed for a cold region and were outfitted with ski boots, fleece-lined parkas, and other winter equipment.

Specialists in missile construction, under the guise of machine operators and agricultural specialists, arrived in July. A total of 43,000 foreign troops would ultimately be brought in. Chief Marshal of Artillery Sergey Biryuzov, Head of the Soviet Rocket Forces, led a survey team that visited Cuba. He told Khrushchev that the missiles would be concealed and camouflaged by palm trees. The Soviet troops would arrive in Cuba heavily underprepared. They did not know that the tropical climate would render ineffective many of their weapons and much of their equipment. In the first few days of setting up the missiles, troops complained of fuse failures, excessive corrosion, overconsumption of oil, and generator blackouts.

As early as August 1962, the US suspected that the Soviets were building missile facilities in Cuba. During that month, its intelligence services gathered information of sightings by ground observers of Soviet-built MiG-21 fighters and Il-28 light bombers. U-2 spy planes found S-75 Dvina (NATO designation SA-2) surface-to-air missile sites at eight different locations. CIA director John A. McCone was suspicious. Sending antiaircraft missiles into Cuba, he reasoned, "made sense only if Moscow intended to use them to shield a base for ballistic missiles aimed at the United States". On 10 August, he wrote a memo to Kennedy in which he guessed that the Soviets were preparing to introduce ballistic missiles into Cuba. Che Guevara himself traveled to the Soviet Union on 30 August 1962, to sign the final agreement regarding the deployment of missiles in Cuba. The visit was heavily monitored by the CIA as Guevara was being watched closely by American intelligence. While in the Soviet Union, Guevara argued with Khrushchev that the missile deal should be made public but Khrushchev insisted on total secrecy, and promised the Soviet Union's support if the Americans discovered the missiles. By the time Guevara arrived in Cuba, U-2 spy planes had already discovered the Soviet troops in Cuba.

With important Congressional elections scheduled for November, the crisis became enmeshed in American politics. On 31 August, Senator Kenneth Keating (R-New York) warned on the Senate floor that the Soviet Union was "in all probability" constructing a missile base in Cuba. He charged the Kennedy administration with covering up a major threat to the US, thereby starting the crisis. He may have received this initial "remarkably accurate" information from his friend, former congresswoman and ambassador Clare Boothe Luce, who in turn received it from Cuban exiles. A later confirming source for Keating's information may have been the West German ambassador to Cuba, who had received information from dissidents inside Cuba that Soviet troops had arrived in Cuba in early August and were seen working "in all probability on or near a missile base". The ambassador passed this information to Keating on a trip to Washington in early October. Air Force General Curtis LeMay presented a pre-invasion bombing plan to Kennedy in September, and spy flights and minor military harassment from US forces at Guantanamo Bay Naval Base were the subject of continual Cuban diplomatic complaints to the US government.

The first consignment of Soviet R-12 missiles arrived on the night of 8 September, followed by a second on 16 September. The R-12 was a medium-range ballistic missile capable of carrying a thermonuclear warhead. It was a single-stage, road-transportable, surface-launched, storable liquid propellant-fuelled missile that could deliver a megaton-class nuclear weapon. The Soviets were building nine sites, six for R-12 medium-range missiles (NATO designation SS-4 Sandal) with an effective range of 2,000 kilometres (1,200 mi) and three for R-14 intermediate-range ballistic missiles (NATO designation SS-5 Skean) with a maximum range of 4,500 kilometres (2,800 mi).

On 7 October, Cuban President Osvaldo Dorticós Torrado spoke at the UN General Assembly: "If... we are attacked, we will defend ourselves. I repeat, we have sufficient means with which to defend ourselves; we have indeed our inevitable weapons, the weapons, which we would have preferred not to acquire, and which we do not wish to employ." On 11 October in another Senate speech, Sen Keating reaffirmed his earlier warning of 31 August and stated that, "Construction has begun on at least a half dozen launching sites for intermediate range tactical missiles."

The Cuban leadership was further upset when on 20 September, the US Senate approved Joint Resolution 230, which stated that the US was determined "to prevent in Cuba the creation or use of an externally-supported military capability endangering the security of the United States". On the same day, the US announced a major military exercise in the Caribbean, PHIBRIGLEX-62, which Cuba denounced as a deliberate provocation and proof that the US planned to invade Cuba.

The Soviet leadership believed, based on its perception of Kennedy's lack of confidence during the Bay of Pigs Invasion, that he would avoid confrontation and would accept the missiles as a fait accompli. On 11 September, the Soviet Union publicly warned that a US attack on Cuba or on Soviet ships that were carrying supplies to the island would mean war. The Soviets continued the Maskirovka program to conceal their actions in Cuba. They repeatedly denied that the weapons being brought into Cuba were offensive in nature. On 7 September, Soviet Ambassador to the United States Anatoly Dobrynin assured United States Ambassador to the United Nations Adlai Stevenson that the Soviet Union was supplying only defensive weapons to Cuba. On 11 September, the Telegraph Agency of the Soviet Union (TASS: Telegrafnoe Agentstvo Sovetskogo Soyuza) announced that the Soviet Union had no need or intention to introduce offensive nuclear missiles into Cuba.

Missiles placed in Cuba would enable the Soviets to target most of the continental US. The planned arsenal consisted of forty launchers. The Cuban populace observed the arrival and deployment of the missiles and hundreds of reports reached Miami. US intelligence received countless reports, many of dubious quality or even laughable, most of which could be dismissed as describing defensive missiles.

Only five reports bothered the analysts. They described large trucks passing through towns at night that were carrying very long canvas-covered cylindrical objects and could not make turns through towns without backing up and maneuvering. Defensive missile transporters, it was believed, could make such turns without undue difficulty. The reports could not be satisfactorily dismissed.

The United States had been sending U-2 surveillance flights over Cuba since the failed Bay of Pigs Invasion. A pause in reconnaissance flights occurred on 30 August 1962 when a U-2 operated by the US Air Force's Strategic Air Command flew over Sakhalin Island in the Soviet Far East by mistake. The Soviets lodged a protest and the US apologized. Nine days later, a Taiwanese-operated U-2 was lost over western China to an SA-2 surface-to-air missile (SAM). US officials were worried that one of the Cuban or Soviet SAMs in Cuba might shoot down a CIA U-2, causing another international incident. In a meeting with members of the Committee on Overhead Reconnaissance (COMOR) on 10 September 1962, Secretary of State Dean Rusk and National Security Advisor McGeorge Bundy restricted further U-2 flights over Cuban airspace. The resulting lack of coverage over the island for the next five weeks became known to historians as the "Photo Gap". No significant U-2 coverage was achieved over the interior of the island during this time. US officials attempted to use a Corona photo-reconnaissance satellite to photograph reported Soviet military deployments, but the imagery acquired over western Cuba by a Corona KH-4 mission on 1 October 1962 was obscured by clouds and haze and did not provide usable intelligence. At the end of September, Navy reconnaissance aircraft photographed the Soviet ship Kasimov with large crates on its deck the size and shape of Il-28 jet bomber fuselages.

In September 1962, analysts from the Defense Intelligence Agency (DIA) noticed that Cuban surface-to-air missile sites were arranged in a pattern similar to those used by the Soviet Union to protect ICBM bases, and the DIA lobbied for resumption of U-2 flights over the island. In the past the flights had been conducted by the CIA, but pressure from the Defense Department led to that authority being transferred to the Air Force. After the loss of a CIA U-2 over the Soviet Union in May 1960, it was thought that if another U-2 were shot down, an Air Force aircraft apparently being used for a legitimate military purpose would be easier to explain than a CIA flight.

When reconnaissance missions were permitted again, on 9 October 1962, poor weather kept the planes from flying. The US first obtained U-2 photographic evidence of the Soviet missiles on 14 October 1962, when a U-2 flight piloted by Major Richard Heyser took 928 pictures on a path selected by DIA analysts, capturing images of what turned out to be an SS-4 construction site at San Cristóbal, Pinar del Río Province (now in Artemisa Province), in western Cuba.

On 15 October 1962, the CIA's National Photographic Interpretation Center (NPIC) reviewed the U-2 photographs and identified objects that appeared to be medium range ballistic missiles. This identification was made partly on the strength of reporting provided by Oleg Penkovsky, a double agent in the GRU working for the CIA and MI6. Although he provided no direct reports of Soviet missile deployments to Cuba, technical and doctrinal details of Soviet missile regiments that had been provided by Penkovsky in the months and years prior to the crisis helped NPIC analysts to identify the missiles in U-2 imagery.

That evening, the CIA notified the Department of State and at 8:30 pm EDT, Bundy chose to wait until the next morning to tell the President. McNamara was briefed at midnight. The next morning, Bundy showed Kennedy the U-2 photographs and briefed him on the CIA's analysis of the images. At 6:30 pm EDT, Kennedy convened a meeting of the nine members of the National Security Council and five other key advisers, in a group he named the Executive Committee of the National Security Council (EXCOMM) after the fact on 22 October by National Security Action Memorandum 196. Without informing the members of EXCOMM, President Kennedy tape-recorded all of their proceedings, and Sheldon M. Stern, head of the Kennedy library transcribed some of them.

On 16 October, President Kennedy notified Attorney General Robert Kennedy that he was convinced the Soviets were placing missiles on Cuba, that it was a legitimate threat and that the possibility of nuclear destruction by two world superpowers had become a reality. Robert Kennedy responded by contacting the Soviet Ambassador, Anatoly Dobrynin. Robert Kennedy expressed his "concern about what was happening" and Dobrynin "was instructed by Soviet Chairman Nikita S. Khrushchev to assure President Kennedy that there would be no ground-to-ground missiles or offensive weapons placed in Cuba". Khrushchev further assured Kennedy that the Soviet Union had no intention of "disrupting the relationship of our two countries" despite the photo evidence presented before President Kennedy.

The US had no plan for a response in place because it had never expected that the Soviets would install nuclear missiles on Cuba. EXCOMM discussed several possible courses of action:

Do nothing: American vulnerability to Soviet missiles was not new.

Diplomacy: Use diplomatic pressure to induce the Soviet Union to remove the missiles.

Secret approach: Offer Castro the choice of parting from the Soviets or being invaded.

Invasion: Full-force invasion of Cuba and overthrow of Castro.

Air strike: Use the US Air Force to attack all known missile sites.

Blockade: Use the US Navy to block any missiles from arriving in Cuba.

The Joint Chiefs of Staff unanimously agreed that a full-scale attack and invasion was the only solution. They believed that the Soviets would not attempt to stop the US from conquering Cuba. Kennedy was skeptical:

They, no more than we, can let these things go by without doing something. They can't, after all their statements, permit us to take out their missiles, kill a lot of Russians, and then do nothing. If they don't take action in Cuba, they certainly will in Berlin.

Kennedy concluded that attacking Cuba by air would signal the Soviets to presume "a clear line" to conquer Berlin. Kennedy also believed that US allies would think of the country as "trigger-happy cowboys" who lost Berlin because they could not peacefully resolve the Cuban situation.

EXCOMM considered the effect on the strategic balance of power, both political and military. The Joint Chiefs of Staff believed that the missiles would seriously alter the military balance, but McNamara disagreed. An extra 40, he reasoned, would make little difference to the overall strategic balance. The US already had approximately 5,000 strategic warheads, but the Soviet Union had only 300. McNamara concluded that the Soviets having 340 would not therefore substantially alter the strategic balance. In 1990, he reiterated that "it made no difference.... The military balance wasn't changed. I didn't believe it then, and I don't believe it now."

It was agreed that the missiles would affect the political balance. Kennedy had explicitly promised the American people less than a month before the crisis that "if Cuba should possess a capacity to carry out offensive actions against the United States... the United States would act." Further, US credibility among its allies and people would be damaged if the Soviet Union appeared to redress the strategic imbalance by placing missiles in Cuba. Kennedy explained after the crisis that "it would have politically changed the balance of power. It would have appeared to, and appearances contribute to reality."

On 18 October 1962, Kennedy met Soviet Minister of Foreign Affairs Andrei Gromyko, who claimed that the weapons were for defensive purposes only. Not wanting to expose what he already knew and to avoid panicking the American public, Kennedy did not reveal that he was already aware of the missile buildup.

Two Operational Plans (OPLAN) were considered. OPLAN 316 envisioned a full invasion of Cuba by Army and Marine units, supported by the Navy, following Air Force and naval airstrikes. Army units in the US would have had difficulty fielding mechanised and logistical assets, and the US Navy could not supply enough amphibious shipping to transport even a modest armoured contingent from the Army.

OPLAN 312, primarily an Air Force and Navy carrier operation, was designed with enough flexibility to do anything from engaging individual missile sites to providing air support for OPLAN 316's ground forces.

Kennedy conferred with members of EXCOMM and other top advisers throughout 21 October and considered the two remaining options: an air strike primarily against the Cuban missile bases or a naval blockade of Cuba. A full-scale invasion was not the administration's first option. McNamara supported the naval blockade as a strong but limited military action that would leave the US in control. The term "blockade" was problematic – according to international law, a blockade is an act of war, but the Kennedy administration did not think that the Soviets would be provoked to attack by a mere blockade. Legal experts at the State Department and Justice Department concluded that a declaration of war could be avoided if another legal justification, based on the Rio Treaty for defence of the Western Hemisphere, was obtained from a resolution by a two-thirds vote from the members of the Organization of American States (OAS).

Admiral George Anderson, Chief of Naval Operations wrote a position paper that helped Kennedy to differentiate between what they termed a "quarantine" of offensive weapons and a blockade of all materials, claiming that a classic blockade was not the original intention. Since it would take place in international waters, Kennedy obtained the approval of the OAS for military action under the hemispheric defence provisions of the Rio Treaty:

Latin American participation in the quarantine now involved two Argentine destroyers which were to report to the US Commander South Atlantic [COMSOLANT] at Trinidad on November 9. An Argentine submarine and a Marine battalion with lift were available if required. In addition, two Venezuelan destroyers (Destroyers ARV D-11 Nueva Esparta" and "ARV D-21 Zulia") and one submarine (Caribe) had reported to COMSOLANT, ready for sea by November 2. The Government of Trinidad and Tobago offered the use of Chaguaramas Naval Base to warships of any OAS nation for the duration of the "quarantine". The Dominican Republic had made available one escort ship. Colombia was reported ready to furnish units and had sent military officers to the US to discuss this assistance. The Argentine Air Force informally offered three SA-16 aircraft in addition to forces already committed to the "quarantine" operation.

This initially was to involve a naval blockade against offensive weapons within the framework of the Organization of American States and the Rio Treaty. Such a blockade might be expanded to cover all types of goods and air transport. The action was to be backed up by surveillance of Cuba. The CNO's scenario was followed closely in later implementing the "quarantine."

On 19 October, the EXCOMM formed separate working groups to examine the air strike and blockade options, and by the afternoon most support in the EXCOMM had shifted to a blockade. Reservations about the plan continued to be voiced as late as 21 October, the paramount concern being that once the blockade was put into effect, the Soviets would rush to complete some of the missiles and the US could find itself bombing operational missiles if the blockade had not already forced their removal.

At 3:00 pm EDT on 22 October 1962, President Kennedy formally established the executive committee (EXCOMM) with National Security Action Memorandum (NSAM) 196. At 5:00 pm, he met Congressional leaders, who opposed a blockade and demanded a stronger response. In Moscow, US Ambassador Foy D. Kohler briefed Khrushchev on the pending blockade and Kennedy's speech to the nation. Ambassadors around the world gave notice to non-Eastern Bloc leaders. Before the speech, US delegations met Canadian Prime Minister John Diefenbaker, British Prime Minister Harold Macmillan, West German Chancellor Konrad Adenauer, French President Charles de Gaulle and Secretary-General of the Organization of American States, José Antonio Mora to brief them on this intelligence and the US's proposed response. All were supportive of the US position. Over the course of the crisis, Kennedy had daily telephone conversations with Macmillan, who was publicly supportive of US actions.

Shortly before his speech, Kennedy telephoned former President Dwight Eisenhower. Kennedy's conversation with the former president also revealed that the two had been consulting during the Cuban Missile Crisis. The two also anticipated that Khrushchev would respond to the Western world in a manner similar to his response during the Suez Crisis, and would possibly wind up trading off Berlin.

At 7:00 pm EDT on 22 October, Kennedy delivered a nationwide televised address on all of the major networks announcing the discovery of the missiles. He noted:

It shall be the policy of this nation to regard any nuclear missile launched from Cuba against any nation in the Western Hemisphere as an attack by the Soviet Union on the United States, requiring a full retaliatory response upon the Soviet Union.

Kennedy described the administration's plan:

To halt this offensive buildup, a strict quarantine on all offensive military equipment under shipment to Cuba is being initiated. All ships of any kind bound for Cuba, from whatever nation or port, will, if found to contain cargoes of offensive weapons, be turned back. This quarantine will be extended, if needed, to other types of cargo and carriers. We are not at this time, however, denying the necessities of life as the Soviets attempted to do in their Berlin blockade of 1948.

During the speech, a directive went out to all US forces worldwide, placing them on DEFCON 3. The heavy cruiser USS Newport News was the designated flagship for the blockade, with USS Leary as Newport News's destroyer escort. Kennedy's speech writer Ted Sorensen stated in 2007 that the address to the nation was "Kennedy's most important speech historically, in terms of its impact on our planet."

On 23 October 1962, US Air Force RF-101A/C Voodoos and US Navy RF-8A Crusaders began flying extremely hazardous low-level photo reconnaissance missions over Cuba. Only once did the Cuban Air Force scramble a MiG-19 to attempt a shoot-down, but the attempt was unsuccessful.

At 11:24 am EDT on 24 October, a cable from US Under Secretary of State George Ball to the US Ambassadors in Turkey and NATO notified them that they were considering making an offer to withdraw missiles from Italy and Turkey in exchange for Soviet withdrawal from Cuba. Turkish officials replied that they would "deeply resent" any trade involving the US missile presence in their country. One day later, on the morning of 25 October, American journalist Walter Lippmann proposed the same thing in his syndicated column. Castro reaffirmed Cuba's right to self-defense and said that all of its weapons were defensive and Cuba would not allow an inspection.

In the United Kingdom, Prime Minister Harold Macmillan supported Kennedy's response. The British ambassador to the United States, David Ormsby-Gore, was a close family friend of the Kennedys and actively involved in White House discussions on how to resolve the crisis.

In West Germany, newspapers supported the US response by contrasting it with the weak American actions in the region during the preceding months. They also expressed some fear that the Soviets might retaliate in Berlin. The West German government was supportive of the blockade.

In France on 23 October, the crisis made the front page of all the daily newspapers. The next day, an editorial in Le Monde expressed doubt about the authenticity of the CIA's photographic evidence. Two days later, after a visit by a high-ranking CIA agent, the newspaper accepted the validity of the photographs. French President Charles de Gaulle gave Kennedy his full support, but he viewed the crisis as a demonstration of Europe's vulnerability to superpower conflict.

On 24 October, Pope John XXIII sent a message to the Soviet embassy in Rome, to be transmitted to the Kremlin, in which he voiced his concern for peace. In this message he stated, "We beg all governments not to remain deaf to this cry of humanity. That they do all that is in their power to save peace."

Three days after Kennedy's speech, the Chinese People's Daily announced that "650,000,000 Chinese men and women were standing by the Cuban people." The crisis coincided with the Sino-Indian War, with China launching a surprise attack on India at the Himalayan border.

The Organization of American States (OAS) backed the United States' naval quarantine, condemned the Soviet missile buildup in Cuba and voted to take measures to prevent more offensive weapons from reaching Cuba.

In the 29 October issue of Le Figaro, Raymond Aron wrote in support of the American response.

The crisis continued unabated, and on the evening of 24 October 1962, the Soviet TASS news agency broadcast a telegram from Khrushchev to Kennedy in which Khrushchev warned that the United States' "outright piracy" would lead to war. Khrushchev then sent at 9:24 pm a telegram to Kennedy, which was received at 10:52 pm EDT. Khrushchev stated, "if you weigh the present situation with a cool head without giving way to passion, you will understand that the Soviet Union cannot afford not to decline the despotic demands of the USA". The Soviet Union viewed the blockade as "an act of aggression" and their ships would be instructed to ignore it. After 23 October, Soviet communications with the US increasingly showed indications of having been rushed. Undoubtedly a result of pressure, it was not uncommon for Khrushchev to repeat himself and to send messages lacking basic editing. With President Kennedy making known his aggressive intentions of a possible airstrike followed by an invasion on Cuba, Khrushchev sought a diplomatic compromise. Communications between the two superpowers had entered a new and revolutionary period, with the threat of mutual destruction now accompanying the deployment of nuclear weapons.

The US requested an emergency meeting of the United Nations Security Council on 25 October and Ambassador to the United Nations, Adlai Stevenson, confronted Soviet Ambassador Valerian Zorin and challenged him to admit the existence of the missiles. Ambassador Zorin refused to answer. At 10:00 pm EDT the next day, the US raised the readiness level of Strategic Air Command (SAC) forces to DEFCON 2. For the only confirmed time in US history, B-52 bombers were put on continuous airborne alert. B-47 medium bombers were dispersed to military and civilian airfields and made ready to take off, fully equipped, at 15 minutes' notice. One-eighth of SAC's 1,436 bombers were on airborne alert. Some 145 intercontinental ballistic missiles, some of which targeted Cuba, were placed on alert. Air Defense Command (ADC) redeployed 161 nuclear-armed interceptors to 16 dispersal fields within nine hours, with one third on 15-minute alert status. Twenty-three nuclear-armed B-52 bombers were sent to orbit points within striking distance of the Soviet Union to demonstrate that the US was serious. Jack J. Catton later estimated that about 80 per cent of SAC's planes were ready for launch during the crisis. David A. Burchinal recalled that, by contrast:

the Russians were so thoroughly stood down, and we knew it. They didn't make any move. They did not increase their alert; they did not increase any flights, or their air defense posture. They didn't do a thing, they froze in place. We were never further from nuclear war than at the time of Cuba, never further.

By 22 October, Tactical Air Command (TAC) had 511 fighters plus supporting tankers and reconnaissance aircraft deployed to face Cuba on one-hour alert status. TAC and the Military Air Transport Service had problems: the concentration of aircraft in Florida strained command and support echelons, which were facing critical undermanning in security, armaments, and communications.

At 1:00 pm EDT on 26 October, John A. Scali of ABC News met Aleksandr Fomin, the cover name of Alexander Feklisov, the KGB station chief in Washington, at Fomin's request. Following the instructions of the Politburo of the CPSU, Fomin noted, "War seems about to break out." He asked Scali to use his contacts to talk to his "high-level friends" at the State Department to see if the US would be interested in a diplomatic solution. He suggested that the language of the deal would contain an assurance from the Soviet Union to remove the weapons under UN supervision and that Castro would publicly announce that he would not accept such weapons again, in exchange for a public statement by the US that it would not invade Cuba. The US responded by asking the Brazilian government to pass a message to Castro that the US would be "unlikely to invade" if the missiles were removed.

At 6:00 pm EDT on 26 October, the State Department started receiving a message that appeared to be written personally by Khrushchev. It was Saturday 2:00 am in Moscow. The long letter took several minutes to arrive, and it took translators additional time to translate and transcribe it.

Robert F. Kennedy described the letter as "very long and emotional". Khrushchev reiterated the basic outline that had been stated to Scali earlier in the day: "I propose: we, for our part, will declare that our ships bound for Cuba are not carrying any armaments. You will declare that the United States will not invade Cuba with its troops and will not support any other forces which might intend to invade Cuba. Then the necessity of the presence of our military specialists in Cuba will disappear." At 6:45 pm EDT, news of Fomin's offer to Scali was finally heard and was interpreted as a "set up" for the arrival of Khrushchev's letter. The letter was then considered official and accurate, although it was later learned that Fomin was almost certainly operating without official backing. Additional study of the letter was ordered and continued into the night.

Direct aggression against Cuba would mean nuclear war. The Americans speak about such aggression as if they did not know or did not want to accept this fact. I have no doubt they would lose such a war.

Castro, on the other hand, was convinced that an invasion of Cuba was imminent, and on 26 October he sent a telegram to Khrushchev that appeared to call for a pre-emptive nuclear strike on the US in case of attack. In a 2010 interview, Castro expressed regret about his 1962 stance on first use: "After I've seen what I've seen, and knowing what I know now, it wasn't worth it at all." Castro also ordered all anti-aircraft weapons in Cuba to fire on any US aircraft. Previous orders had been to fire only on groups of two or more. At 6:00 am EDT on 27 October, the CIA delivered a memo reporting that three of the four missile sites at San Cristobal and both sites at Sagua la Grande appeared to be fully operational. It also noted that the Cuban military continued to organise for action but was under order not to act unless attacked.

At 9:00 am EDT on 27 October, Radio Moscow began broadcasting a message from Khrushchev. Contrary to the letter of the night before, the message offered a new trade: the missiles on Cuba would be removed in exchange for the removal of the Jupiter missiles from Italy and Turkey. At 10:00 am EDT, the executive committee met again to discuss the situation and came to the conclusion that the change in the message was because of internal debate between Khrushchev and other party officials in the Kremlin. Kennedy realised that he would be in an "insupportable position if this becomes Khrushchev's proposal" because the missiles in Turkey were not militarily useful and were being removed anyway, and "It's gonna – to any man at the United Nations or any other rational man, it will look like a very fair trade." Bundy explained why Khrushchev's public acquiescence could not be considered: "The current threat to peace is not in Turkey, it is in Cuba."

McNamara noted that another tanker, the Grozny, was about 600 miles (970 km) out and should be intercepted. He also noted that they had not made the Soviets aware of the blockade line and suggested relaying that information to them via U Thant at the United Nations.

While the meeting progressed, at 11:03 am EDT a new message began to arrive from Khrushchev. The message stated, in part:

You are disturbed over Cuba. You say that this disturbs you because it is ninety-nine miles by sea from the coast of the United States of America. But... you have placed destructive missile weapons, which you call offensive, in Italy and Turkey, literally next to us.... I therefore make this proposal: We are willing to remove from Cuba the means which you regard as offensive.... Your representatives will make a declaration to the effect that the United States... will remove its analogous means from Turkey... and after that, persons entrusted by the United Nations Security Council could inspect on the spot the fulfillment of the pledges made.

The executive committee continued to meet through the day.

Throughout the crisis, Turkey had repeatedly stated that it would be upset if the Jupiter missiles were removed. Italy's Prime Minister Amintore Fanfani, who was also Foreign Minister ad interim, offered to allow withdrawal of the missiles deployed in Apulia as a bargaining chip. He gave the message to one of his most trusted friends, Ettore Bernabei, general manager of RAI-TV, to convey to Arthur M. Schlesinger Jr. Bernabei was in New York to attend an international conference on satellite TV broadcasting.

On Saturday, October 27, USAF Major Rudolf Anderson took off on his sixth mission over Cuba in a U-2F Dragon Lady (AF Serial Number 56-6676, former CIA Article 343 - the third CIA U-2A, modified for air-to-air refuelling), from a forward operating location at McCoy Air Force Base in Orlando, Florida. A few hours into his mission, at approximately 12:00 pm EDT, he was shot down over Banes, Cuba, by one of two Soviet-supplied S-75 Dvina (NATO designation SA-2 Guideline) surface-to-air missiles that were fired at his aircraft per the order of two Soviet generals (Soviet Forces Deputy Commander Major General Leonid Garbuz & Deputy Commander of Air Defenses Lieutenant General Stepan Grechko), both of whom were stationed in a command center in Havana. Before giving this order, they attempted to obtain authorization from their superior officer Army General Issa Pliyev (Commander of all Soviet forces in Cuba during Operation Anadyr), but after finding that Pliyev was unreachable (possibly due to illness) they decided to authorize the shoot-down themselves. The aircraft crashed, and Anderson was killed. Later that day, at about 3:41 pm EDT, several US Navy RF-8A Crusader aircraft, on low-level photo-reconnaissance missions, were fired upon.

At 4:00 pm EDT, Kennedy recalled members of EXCOMM to the White House and ordered that a message should immediately be sent to U Thant asking the Soviets to suspend work on the missiles while negotiations were carried out. During the meeting, General Maxwell Taylor delivered the news that the U-2 had been shot down. Kennedy had earlier claimed he would order an attack on such sites if fired upon, but he decided to not act unless another attack was made. On 28 October 1962, Khrushchev told his son Sergei that the shooting down of Anderson's U-2 was by the "Cuban military at the direction of Raúl Castro".

On 27 October Bobby Kennedy relayed a message to the Soviet Ambassador that President Kennedy was under pressure from the military to use force against Cuba and that "an irreversible chain of events could occur against his will" as "the president is not sure that the military will not overthrow him and seize power". He therefore implored Khrushchev to accept Kennedy's proposed agreement.

Forty years later, McNamara said:

We had to send a U-2 over to gain reconnaissance information on whether the Soviet missiles were becoming operational. We believed that if the U-2 was shot down that—the Cubans didn't have capabilities to shoot it down, the Soviets did—we believed if it was shot down, it would be shot down by a Soviet surface-to-air-missile unit, and that it would represent a decision by the Soviets to escalate the conflict. And therefore, before we sent the U-2 out, we agreed that if it was shot down we wouldn't meet, we'd simply attack. It was shot down on Friday.... Fortunately, we changed our mind, we thought "Well, it might have been an accident, we won't attack." Later we learned that Khrushchev had reasoned just as we did: we send over the U-2, if it was shot down, he reasoned we would believe it was an intentional escalation. And therefore, he issued orders to Pliyev, the Soviet commander in Cuba, to instruct all of his batteries not to shoot down the U-2.

Daniel Ellsberg said that Robert Kennedy (RFK) told him in 1964 that after the U-2 was shot down and the pilot killed, he (RFK) told Soviet ambassador Dobrynin, "You have drawn first blood ... . [T]he president had decided against advice ... not to respond militarily to that attack, but he [Dobrynin] should know that if another plane was shot at, ... we would take out all the SAMs and anti-aircraft ... . And that would almost surely be followed by an invasion."

Emissaries sent by both Kennedy and Khrushchev agreed to meet at the Yenching Palace Chinese restaurant in the Cleveland Park neighbourhood of Washington, DC, on Saturday evening, 27 October. Kennedy suggested taking Khrushchev's offer to trade away the missiles. Unknown to most members of the EXCOMM, but with the support of his brother the president, Robert Kennedy had been meeting the Soviet Ambassador Dobrynin in Washington to discover whether the intentions were genuine. The EXCOMM was against the proposal because it would undermine NATO's authority, and the Turkish government had repeatedly stated that it was against any such trade.

As the meeting progressed, a new plan emerged, and Kennedy was slowly persuaded. The new plan called for him to ignore the latest message and instead to return to Khrushchev's earlier one. Kennedy was initially hesitant, feeling that Khrushchev would no longer accept the deal because a new one had been offered, but Llewellyn Thompson argued that it was still possible. White House Special Counsel and Adviser Ted Sorensen and Robert Kennedy left the meeting and returned 45 minutes later, with a draft letter to that effect. The President made several changes, had it typed, and sent it.

After the EXCOMM meeting, a smaller meeting continued in the Oval Office. The group argued that the letter should be underscored with an oral message to Dobrynin that stated that if the missiles were not withdrawn, military action would be used to remove them. Rusk added one proviso that no part of the language of the deal would mention Turkey, but there would be an understanding that the missiles would be removed "voluntarily" in the immediate aftermath. The president agreed, and the message was sent.

At Rusk's request, Fomin and Scali met again. Scali asked why the two letters from Khrushchev were so different, and Fomin claimed it was because of "poor communications". Scali replied that the claim was not credible and shouted that he thought it was a "stinking double cross". He went on to claim that an invasion was only hours away, and Fomin stated that a response to the US message was expected from Khrushchev shortly and urged Scali to tell the State Department that no treachery was intended. Scali said that he did not think anyone would believe him, but he agreed to deliver the message. The two went their separate ways, and Scali immediately typed out a memo for the EXCOMM.

Within the US establishment, it was understood that ignoring the second offer and returning to the first put Khrushchev in a terrible position.