On July 1, 1968, the Nuclear Non-Proliferation Treaty was opened for signature in Washington, London, and Moscow. In force since March 5, 1970, it has become the most widely joined arms control agreement in history, with 191 states parties, and it commits its members to three “pillars”: non-proliferation, disarmament — the right to peaceful nuclear energy under safeguards.
For the rest of nuclear proliferation beyond the superpowers.
The first overview is non-proliferation. Article I forbids nuclear-weapon states from transferring nuclear weapons to any recipient. Article II forbids non-nuclear-weapon states from receiving or manufacturing them. The first two articles are the technical heart of the treaty, and they have been remarkably successful: the number of nuclear-weapon states has grown from five in 1964 to nine in 2024.
The second overview is disarmament. Article VI commits all parties to pursue negotiations in good faith on effective measures relating to nuclear disarmament. The 2000 Review Conference produced an “unequivocal undertaking” by the nuclear-weapon states to accomplish the total elimination of their arsenals. The 2010, 2015, and 2022 review conferences produced more limited consensus, disarmament overview remains the most fragile element of the regime.
The third overview is the right to peaceful nuclear energy, under IAEA safeguards. Article IV recognizes “the inalienable right” of all parties to develop nuclear energy for peaceful purposes. The right is conditioned on safeguards, including the Additional Protocol of 1997, which gives the IAEA broader inspection rights.
The NPT’s principal success is that the number of nuclear-armed states has remained small. The NPT’s principal failure is the persistence of the nuclear-weapon states’ modernization programs. The NPT’s structural vulnerability is that the bargain — non-proliferation in exchange for disarmament — is asymmetric: non-nuclear-weapon states have held up their end, and the disarmament overview has been honored in form more than in substance.