The Cuban Missile Crisis and nuclear testing

Read also the related OP-ed by CTBTO Executive Secretary Tibor Tóth, A nuclear world - 50 years after Cuban Missile 'Crisis,' the world waits to move back the hands on doomsday clock (Chicago Tribune, 26 October 2012).
October 2012 marks the 50th anniversary of the Cuban Missile Crisis. It was triggered on 16 October 1962 when the United States discovered that the Soviet Union had stationed nuclear capable missiles in Cuba, placing Washington and other major cities within reach. This discovery came amidst a political climate already marked by tension and an intensifying nuclear arms race: In the 16 months before this, both superpowers had conducted over 250 nuclear tests, more than in the 16 preceding years together.
The United States reacted by implementing a blockade or “quarantine”, preventing Soviet ships from delivering further weapons to Cuba. In addition, President Kennedy’s military advisors were pushing for an invasion of Cuba, a step that would undoubtedly have caused a nuclear escalation: Unknown to the United States, over 100 tactical nuclear warheads were already on Cuban soil. Local Soviet commanders had even readied these systems by “mating” the warheads with the missiles, without authorization from Moscow.

During the crisis, a number of events ensued that could have precipitated an outbreak of hostilities. Two of them occurred towards the end of the crisis: in the evening of 27 October, U.S. Air Force Major Rudolph Anderson, Jr. was shot down in his U-2 spy plane and killed whilst flying a reconnaissance mission over Cuba. In response, U.S. military leaders unanimously urged Kennedy to bomb Cuba. He refused.

Later that same evening, in waters near Cuba, the destroyer USS Cony fired depth charges near a Soviet B-59 submarine in an effort to force the soviet submarine to the surface. Cut off from communications with Moscow, and under the impression that war had started, Captain Vitali Grigorievitch Savitsky wanted to retaliate by launching the nuclear-tipped torpedo warhead that the vessel was carrying. The United States did not know of this nuclear armament. However, naval officer Vasili Arkhipov refused to grant his authorization that was required for the nuclear attack and persuaded the captain to surface and await orders from Moscow. This fact was only revealed in 2002 at a conference to mark the 40th anniversary of the crisis.
After tense negotiations, the crisis ended on 28 October when Chairman Khrushchev agreed to the removal of Soviet nuclear weapons from Cuban soil. In return, President Kennedy agreed to the non-publicised removal of U.S. missiles from Turkey and gave assurances that the United States would not to invade Cuba or assist others in doing so.

Heeding the wake-up call In the following months, both parties, alongside the United Kingdom, continued negotiations on banning nuclear testing. While a comprehensive ban on all nuclear tests was on the table, only a partial ban could be achieved owing to pressure from the military establishment on both sides. The 1963 Partial Test Ban Treaty (PTBT) bans nuclear testing above ground, in the atmosphere, in outer space and under water, but not underground.

While the PTBT limited the atmospheric fallout from nuclear tests, nuclear testing subsequently not only continued, but increased in number, enabling the development of ever more destructive nuclear weapons by an increasing number of countries. Only the 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear tests.