The Flexible response was a policy implemented by President John F. Kennedy in 1961 in order to substitute the New Look and the massive retaliation policy that Dwight Eisenhower's had introduced, which consisted on responding using a greater force in case of an attack, and such force involved nuclear weapons.
On the other hand, the flexible response policy aknowledges the Mutual assured destruction if nuclear weapons are involved, as the enemy with shoot back too. It aimed to provide a manner of responding to agression across the spectrum of war but without the employment of nuclear weapons.
When the bomb was finally detonated atop a steel tower, an intense light flash and sudden wave of heat was followed by a great burst of sound echoing in the valley. A ball of fire tore up into the sky and then was surrounded by a giant mushroom cloud stretching some 40,000 feet across. With a power equivalent to around 21,000 tons of TNT, the bomb completely obliterated the steel tower on which it rested. The nuclear age had begun.
