The Joint Chiefs of Staff wanted President Kennedy to take swift and forceful military action. Pushing for an air strike, they also developed plans for an invasion.
Not knowing the Soviets had tactical nuclear weapons on the island, the Pentagon estimated military action would cost around 18,500 lives. Had America invaded, the human cost would have been much greater.
On October 24, while considering military options, the President reached a sobering conclusion. If the United States were to invade Cuba within ten days, some of the Soviet missiles would likely be fired at U.S. targets. Concerned about people in the probable target areas, he pondered (at 2:30 into the tape) whether civilian populations could be evacuated a few days before an invasion.
In the event of U.S. military action, America's allies would have to be briefed. "Selling" the concept - in the face of potentially huge consequences in Berlin - would require deft handling. People involved in that sensitive process have written first-hand accounts of the discussions with America's allies.
In the midst of the turmoil, neither the President nor his brother lost sight of the political implications. Wondering whether challenging the Soviets was the right course of action, JFK expressed his belief that had he done nothing, he would have been impeached. He and Bobby agreed (at 3:43 into the tape) on that issue.
It was up to Adlai Stevenson to test the political waters at the United Nations. Confronting Soviet representatives with proof of their missiles in Cuba, Stevenson (with the help of Colonel David Parker) had a one-way conversation on October 25. The Russians refused to answer.
With no movement by the Kremlin, United States military forces were instructed to move to DEFCON 2 - one step less than maximum readiness. DEFCON 2 had never been reached before. It was not reached again until September 11, 2001.
The superpowers were at the brink of nuclear war.