• Alexander Gillespie is a professor of law at Waikato University.

According to the Doomsday Clock, it is two and a half minutes to midnight.

The Doomsday Clock is an image of how close humanity is to extinction, the figurative midnight. The clock is managed by the board of the Bulletin of Atomic Scientists, in consultation with the board's sponsors, which includes 15 Nobel laureates. The clock was moved forward last month because of the rise of strident nationalism and the comments by Donald Trump about the use and proliferation of nuclear weapons.

The clock has been inching towards this point since 1991, the end of the Cold War when it was wound back to seventeen minutes to midnight. The only point humanity was closer to midnight was in 1953 when it was down to two minutes, directly after the Soviet Union tested its hydrogen bombs.


Today, there are, about 15,000 nuclear weapons on the planet. Broadly, Russia has about 7000; America about 6800; the UK about 215; France 300; China 260; India 120; Pakistan 120; Israel 80 and North Korea 10. For the last five countries, the numbers are best guesses and could be quite wrong.

Similarly, although we know that there is an illegal trade in nuclear materials, and terrorists and/or criminals are trying to get hold of this ultimate weapon, the extent of their progress is a matter of speculation. Although they have been busted 18 times since 1993 with weapons grade material, the amounts needed to make a weapon of mass destruction have not yet, as far as we know, been achieved.

What is more certain is that the magnitude of nuclear weapons of this generation is vastly bigger than what destroyed two cities in Japan, incinerating tens of thousands of people in a flash, a little over 70 years ago. The bomb that destroyed Nagasaki had a yield equivalent to 20,000 tons of TNT. Conversely, the largest nuclear devices today can carry up to 50 megatons (50 million tons of TNT) in one delivery system.

To put this all into some kind of perspective, if the 1500 or so weapons held on high alert, and able to be launched within 15 minutes, were used, their firepower would be the equivalent of all the firepower of World War II, times 300. If these numbers were expanded to include those capable of being launched within a few hours, this would probably take the collective yield to the total firepower of World War II, times 700. Such a full blown exchange would end life on this planet very quickly.

Even a smaller exchange of, say, 50 modern nuclear weapons could kill tens of millions instantly, and the rest of us, slowly. Thus, a relatively small nuclear exchange between Pakistan and India would be sufficient to create a nuclear winter. A nuclear winter is the converse of global warming. It would be where there would be so much pollution in the atmosphere from all of the burning cities that the Earth's ecosystems would not be able to function as they should. That, with the radiation, would probably spell extinction for us as a species over a period of years. There would be no safe place, anywhere, including New Zealand.

Peace held in the cold war because the theory of nuclear deterrence worked. Namely, that there were two rational opponents watching each other, neither wanting themselves, their citizens or children to be incinerated. This fear of a fear of mutually assured destruction kept both sides in check. Rational understanding of risk and oblivion, contained within mutually understood diplomatic practices, meant that the Soviets and the Americans kept their fingers off the trigger.

Today, there are many more actors on the stage and the Soviet Union is gone. Protocols and understandings that kept the balance are being discarded with a frightening regularity. The fear of mutually assured destruction does not necessarily hold terrorists, dictators or megalomaniacs in check.

The concern is that it is no longer just the terrorists and dictators who are irrational. Even if the leaders are rational but just being very antagonistic, concern arises over how the opposition will respond.

In this context, the question is, could an American president start a nuclear war without going through the checks and balance of the American Congress? The short answer is yes.

The only possible break in the chain between the President and the launch of nuclear weapons is the Secretary of Defence, who is required to verify the order. This is not a television reality show.