Given North Korea’s nuclear lunacy, what exactly are the rules, formal or implicit, about which nations can have nuclear weapons and which cannot?
It is complicated.
In the free-for-all environment of the 1940s and 1950s, the original nuclear club included only those countries with the technological know-how, size and money to build nukes. Those realities meant that up until the early 1960s, only Britain, France, the Soviet Union and the United States had nuclear capabilities.
Members of this small club did not worry that many other nations would make such weapons because it seemed far too expensive and difficult for most.
During the Cold War, the Soviet Union and the United States adhered to an unspoken rule that their losing Axis enemies of World War II — Germany, Italy and Japan — should not have nuclear weapons. Despite their financial and scientific ability to obtain them, all three former Axis powers had too much recent historical baggage to be allowed weapons of mass destruction. That tacit agreement apparently still remains.
The Soviet Union and the United States also informally agreed during the Cold War that their own dependent allies who had the ability to go nuclear — including Eastern Bloc nations, most Western European countries, Australia and Canada — would not. Instead, they would depend on their superpower patrons for nuclear deterrence.
By the 1970s, realities had changed again. Large and/or scientifically sophisticated nations such as China (1964), Israel (1967) and India (1974) went nuclear. Often, such countries did so with the help of pro-Western or pro-Soviet patrons and sponsors. The rest of the world apparently shrugged, believing it was inevitable that such nations would obtain nuclear weapons.
The next round of expansion of the nuclear club, however, was far sloppier and more dangerous. Proliferation hinged on whether poorer and…