Kennedy met with members of EXCOMM and other top advisers throughout October 21, considering 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. Robert McNamara supported the naval blockade as a strong but limited military action that left the US in control. However, 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 USSR would be provoked to attack by a mere blockade. Additionally, legal experts at the State Department and Justice Department concluded that a declaration of war could be avoided so long as another legal justification, based on the Rio Treaty for defense of the Western Hemisphere, was obtained via a resolution by a two-thirds vote from the members or the Organization of American States (OAS).
Admiral 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 defense 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 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 October 19, the EXCOMM formed separate working groups to examine the air strike and blockade options, and by the afternoon most support in the EXCOMM shifted to the blockade option. Reservations about the plan continued to be voiced as late as the twenty-first, however, the paramount one being that once the blockade was put into effect, the Soviets would rush to complete some of the missiles. Consequently, the United States could find itself bombing operational missiles were the blockade to fail to force Khrushchev to remove the missiles already on the island.
At 3:00 pm EDT on October 22, President Kennedy formally established the Executive Committee (EXCOMM) with National Security Action Memorandum (NSAM) 196. At 5:00 pm, he met with Congressional leaders who contentiously opposed a blockade and demanded a stronger response. In Moscow, Ambassador Kohler briefed Chairman Khrushchev on the pending blockade and Kennedy's speech to the nation. Ambassadors around the world gave advance notice to non-Eastern Bloc leaders. Before the speech, US delegations met with Canadian Prime Minister John Diefenbaker, British Prime Minister Harold Macmillan, West German Chancellor Konrad Adenauer, and French President Charles de Gaulle to brief them on the US intelligence and their proposed response. All were supportive of the US position.
On October 22 at 7:00 pm EDT, President Kennedy delivered a nation-wide televised address on all of the major networks announcing the discovery of the missiles.
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 designated flagship for the blockade, with the USS Leary (DD-879) as Newport News' destroyer escort.
Read more about this topic: Cuban Missile Crisis