A Club Closed by the Calendar

In March 1963 John F. Kennedy told a press conference that he could imagine a president in the 1970s facing a world with fifteen, twenty or twenty-five nuclear powers. It was a reasonable forecast. Four states had tested by then, a fifth, China, would the following year, and the technology was spreading through civilian programmes everywhere.

The forecast was wrong, and the Non-Proliferation Treaty is a large part of why.

It opened for signature on 1 July 1968 and entered into force in March 1970. Its most revealing line is a definition. For the purposes of the treaty, a nuclear-weapon state is one that manufactured and exploded a nuclear device before 1 January 1967. That captures five countries, the United States, the Soviet Union, Britain, France and China, and it captures them by date rather than by any principle. The club was closed by the calendar.

Everybody else who joined agreed not to acquire the weapon and to accept inspections by the International Atomic Energy Agency. That is the part people remember. The treaty is usually described as a ban with five exceptions, and read that way it can look like an instrument for freezing a hierarchy in place.

But it is written as a bargain, and the other two parts matter as much.

Article IV recognises the inalienable right of all parties to develop nuclear energy for peaceful purposes, and commits those able to help to do so. Article VI commits every party to pursue negotiations in good faith on ending the arms race at an early date and on nuclear disarmament. The non-nuclear states gave up a weapon now. In exchange they received help with reactors and a promise about the future.

Everything since has been an argument about whether that promise has been kept.

The case that it has is stronger than its critics allow. Global stockpiles peaked at roughly seventy thousand warheads in the mid-1980s and stand at around twelve thousand today. Testing has almost stopped. The United States and Russia negotiated a long series of reductions, and the weapons states point out that Article VI sets no deadline and ties nuclear disarmament to a wider goal of general and complete disarmament that nobody is close to.

The case that it has not is just as easy to make. More than half a century after the treaty was signed, the five still hold thousands of weapons, are modernising them on the assumption that they will be kept for decades, and have never negotiated an agreement to eliminate them. The good faith of Article VI looks, to many non-nuclear states, like a promise that can be postponed forever.

That frustration has a date too. In July 2017 a majority of the world's states adopted a Treaty on the Prohibition of Nuclear Weapons, which entered into force in January 2021. None of the nine nuclear-armed states has joined it, and nor have the allies who shelter under their deterrents. It does not bind the states that matter, and it was never expected to. Its purpose is to make the argument about Article VI impossible to ignore.

Then there are the states outside the bargain altogether.

India, Pakistan and Israel never signed. India's objection was principled as well as strategic: a treaty that let five states keep the bomb because they had tested before a certain date looked, from New Delhi, like a permanent ranking. When India tested in 1998, Jaswant Singh, soon to be its foreign minister, defended the decision in an essay titled Against Nuclear Apartheid. North Korea joined and then announced its withdrawal in January 2003, using a clause that allows any party to leave on three months' notice if its supreme interests are jeopardised. It tested its first device in 2006.

So nine nuclear-armed states, not twenty-five. Several countries with the industrial means to build a bomb, among them Japan, Germany, South Korea and Sweden, chose not to, and the treaty gave that choice a framework, a system of inspection and a reputational cost for reversing it.

The review conferences, held every five years, show the strain. Those of 2015 and 2022 both ended without an agreed final document, the first over a proposed zone free of weapons of mass destruction in the Middle East, the second because Russia objected to language about the Zaporizhzhia nuclear plant in occupied Ukraine.

The right way to read the treaty is as a bargain that both sides consider partly broken and neither can afford to abandon. That is an unflattering description, and also a fairly good one of most durable institutions. Its success is measured in the countries that are not on the list, and its weakness in a list that has not got shorter.