One of the most dispiriting features of todays international debates is that the threat to humanity posed by the worlds 23,000 nuclear weapons and by those who would build more of them, or be only too willing to use them has been consigned to the margin of politics. US President Barack Obama did capture global attention with his Prague speech in 2009, which made a compelling case for a nuclear weapon-free world. And he did deliver on a major new arms-reduction treaty with Russia, and hosted a summit aimed at reducing the vulnerability of nuclear weapons and materials to theft or diversion. But nuclear issues still struggle for public resonance and political traction. It would take a brave gambler to bet on ratification of the Comprehensive Test Ban Treaty by the US Senate any time soon. The film An Inconvenient Truth won an Academy Award, led to a Nobel Prize for Al Gore, and attracted huge international attention to the disastrous impact of climate change. But Countdown to Zero, an equally compelling documentary, made by the same production team and making shockingly clear how close and how often the world has come to nuclear catastrophe, has come and gone almost without trace. Complacency trumps anxiety almost everywhere. Japans Fukushima disaster has generated a massive debate about the safety of nuclear power, but not about nuclear weapons. Fear of a nuclear holocaust seems to have ended with the Cold War. Indeed, Hiroshima and Nagasaki seem an eternity ago; new nuclear-weapons states have emerged without the world ending; no terrorist nuclear device has threatened a major city; and possession of nuclear weapons, for the states that have them, seems to be a source of comfort and pride rather than concern or embarrassment. With only a handful of exceptions, the current generation of political leaders shows little interest in disarmament, and not much more in non-proliferation. And their publics are not pressuring them to behave otherwise. Few have worked harder to shake the world out of its complacency than four of the hardest-nosed realists ever to hold public office: former US Secretaries of State Henry Kissinger and George Shultz, former US Secretary of Defence William Perry, and former US Senator Sam Nunn. In a series of opinion articles over the last five years, they have repeatedly sounded the alarm that the risks of nuclear weapons outweigh any possible usefulness in todays security environment. Moreover, they have called for a complete rethinking of deterrence strategy, in order to minimise, and ultimately eliminate, reliance on the most indiscriminately destructive weapons ever invented. Last week in London, the gang of four convened a private meeting with leading think-tank researchers and a worldwide cast of some 30 former foreign and defence ministers, generals, and ambassadors who share their concern and commitment. But our average age was over 65, and the limits of our effectiveness were neatly described by former British Defence Minister Des Browne: People who used to be something really want to tackle this issue. The trouble is that those who are something dont. No quick fix will turn all this around. Getting the kind of messages that emerged from the London meeting embedded in public and political consciousness is going to be slow boring through hard boards. But the messages demand attention, and we simply have to keep drilling. The first message is that the threat of a nuclear weapons catastrophe remains alarmingly real. Existing global stockpiles have a destructive capacity equal to 150,000 Hiroshima bombs, and in handling them there is an omnipresent potential for human error, system error, or miss judgment under stress. India versus Pakistan is a devastating conflict-in-waiting, and North Korea and Iran remain volatile sources of concern. We know that terrorist groups have the capacity to engineer nuclear devices and would explode them anywhere they could; we simply cannot be confident that we can forever deny them access to the fissile material they need to fuel them. The second message is that Cold War nuclear-deterrence doctrine is irrelevant to todays world. So long as nuclear weapons remain, states can justify maintaining a minimum nuclear-deterrent capability. But that can be done without weapons on high alert, and with drastically reduced arsenals in the case of the US and Russia, and, at worst, at current levels for the other nuclear-armed states. The third message is that if the existing nuclear powers sincerely want to prevent others from joining their club, they cannot keep justifying the possession of nuclear weapons as a means of protection for themselves or their allies against other weapons of mass destruction, especially biological weapons, or conventional weapons. Indeed, the single most difficult issue inhibiting serious movement toward disarmament certainly in the case of India versus Pakistan, and Russia and China versus the US are conventional arms imbalances, and ways of addressing them must rise to the top of the policy agenda. The final message is that neither piecemeal change nor sloganeering will do the job. Nuclear disarmament, non-proliferation, counter-terrorism, and civil nuclear-energy risk reduction are inextricably connected, and they call for sustained commitment around a comprehensive agenda, and detailed argument. Sound bites and tweets are an unlikely route to nuclear salvation. Kissinger is no idealist icon. But hes always worth listening to, and never more so than with respect to the question that he has been asking for years: When the next nuclear-weapons catastrophe happens, as it surely will, the world will have to respond dramatically. Why cant we start right now? Gareth Evans, former Australian Foreign Minister, was co-chair of the International Commission on Nuclear Non-Proliferation and Disarmament, and is Convenor of the Asia Pacific Leadership Network. Project Syndicate