Since 1945 when America ushered in the nuclear age with bombs over Hiroshima and Nagasaki, a lot of energy has been devoted to trying to limit the number of countries with nuclear weapons. Nonproliferation, they call it.
An exception was made for Britain, which came up with its bomb in 1952. In 1955, at a summit in Geneva, President Eisenhower tried to persuade Nikita Khrushchev to join in a peaceful atomic program, but the Soviet boss would have none of that. The Soviet Union had already tested its first bomb in 1949, fashioned with the aid of espionage at Los Alamos labs.
Then in 1960, came France, whose notion of French glory required a nuclear force de frappe (nuclear strike force). And, in 1964, China ... and probably in 1967, although never officially confirmed, Israel. The world was getting very unsafe. And so, in 1970, 187 countries signed a nonproliferation treaty, offering to help nations develop peaceful nuclear energy programs if they would forswear weapons and agree to submit to international inspection. That did not keep India from testing its first nuclear weapon in 1974, and Pakistan in 1998.
Every five years the signatories to the treaty would meet, as they have been doing in New York, for some joint nail-biting about who would be the next to crash the nuclear club. Today's top candidates, as you might expect, are North Korea and Iran.
Iran denies it's working on weapons, although without unimpeded inspection it's hard to know. North Korea, which expelled international inspectors, has announced that it has nuclear weapons and hasn't denied reports that it's planning to test one. The White House says if it happens "action would have to be taken," implying punitive measures.
What makes the current situation so complicated is that countries have discovered that the belief that they may have nuclear weapons gives them an enormous bargaining chip in negotiation for economic aid and diplomatic recognition.
An example of the manifold uses of nuclear-development-hinting is Iran, which has advised European powers that it is willing to give negotiation a try before making a "final" decision about resuming its nuclear program.
Just whisper "uranium enrichment" and you gain the anxious ear of the big powers. Six decades into the nuclear age it's harder to tell whether a country is lying when it says it is going nuclear or when it says it isn't.
• Daniel Schorr is the senior news analyst at National Public Radio.