Oct. 23, 1962 - The U.S. blockade against ships delivering offensive weapons to Cuba will go into effect tomorrow at 10 a.m. EST. President Kennedy signed a proclamation of the blockade almost 24 hours after he announced to the nation that he intended to order a naval and air quarantine of Cuba because the Soviet Union had established offensive-missile sites there. The Defense Department decided tonight to make public photographs of the missile sites after the U.S. Embassy in London distributed aerial photographs of them at a news briefing hours earlier. The President declared that Secretary of Defense Robert S. McNamara was empowered to use the land, sea, and air forces of the U.S. and those offered by other members of the Organization of American States to enforce the proclamation. As soon as the proclamation was signed, the U.S. Government immediately sent texts of it in uncoded transmission to the capitals of all nations. The Voice of America also began to broadcast the proclamation on all its channels.