It could have been many more. In 1963, U.S. President John F. Kennedy feared as many as 25 states could have nuclear weapons in the near future—a possibility he regarded as “the greatest possible danger and hazard.” That only nine states have nuclear weapons today is a product of sustained effort, above all by the United States.

As Israel and the United States attack Iran in a bid to deter its ability to produce nuclear weapons, it’s worth reflecting on the fact that in the 80 years since the United States unleashed the first nuclear detonations on Hiroshima and Nagasaki, only eight other countries have gained nuclear weapons: China, France, India, Israel, North Korea, Pakistan, Russia, and the United Kingdom.

As Israel and the United States attack Iran in a bid to deter its ability to produce nuclear weapons, it’s worth reflecting on the fact that in the 80 years since the United States unleashed the first nuclear detonations on Hiroshima and Nagasaki, only eight other countries have gained nuclear weapons: China, France, India, Israel, North Korea, Pakistan, Russia, and the United Kingdom.

It could have been many more. In 1963, U.S. President John F. Kennedy feared as many as 25 states could have nuclear weapons in the near future—a possibility he regarded as “the greatest possible danger and hazard.” That only nine states have nuclear weapons today is a product of sustained effort, above all by the United States.

In each of the four instances that countries have given up nuclear weapons in their possession—South Africa, Belarus, Kazakhstan, and Ukraine—U.S. diplomatic, financial, and technical involvement played a significant role. Over the years, sustained U.S. efforts have also influenced several governments to abandon plans to develop nuclear weapons: Egypt, South Korea, Taiwan, Brazil, Iraq, Libya, and Syria.

And then there are the countries that have the wealth, technological know-how, and arguable security need that could have begun nuclear weapons pro