By Stephan Frühling, associate professor in the Strategic and Defence Centre, ANU, and Andrew O'Neil, professor and dean in the Griffith University Business School.

President Obama's historic visit to Hiroshima was rich in symbolism, but light on substance. Echoing his landmark Prague speech in 2009, Obama recommitted the US to a nuclear-free world, but with no reference to how this would be achieved. The Hiroshima visit and the President's remarks may have been a milestone the nuclear disarmament discourse, but it obscured the favourable light in which nuclear weapons are still seen by many countries.

As unpalatable as it is to advocates of nuclear disarmament, nuclear weapons remain central to the defence and security of a wide range of states. Predictions that nuclear weapons would decline in strategic value have failed to materialise, and they are arguably more significant than ever in shaping key facets of international relations. Importantly, this is the case not only for nuclear-armed states and nuclear wannabees like Iran, but also for the dynamics of America's Asian and European alliances.

While they vary in their levels of anxiety, and therefore in their respective need to be assured by US nuclear guarantees, all of America's allies see extended nuclear deterrence as a symbol of Washington's commitment to their security. For some it is a means of putting off potentially awkward decisions about national nuclear capability. Nuclear weapons form part of the security guarantees the US has extended to allies for several decades. It is most obvious in the case of NATO as a 'nuclear alliance', and is also the case in the bilateral alliances with Japan, South Korea and Australia.

From America's perspective, the nuclear umbrella promotes stability by reducing nuclear proliferation pressures in Asia and Europe while sending a powerful signal to rivals China and Russia that the US regards the security of its allies as indivisible from its own. Extended nuclear deterrence is even more significant in assuring America's Asian allies in relation to North Korea, whose leadership has in recent times issued several direct nuclear threats against South Korea and Japan.

Rather than being foisted on passive US allies, as some argue, the nuclear umbrella remains a key part of alliance relations essentially because of the robust demand among allies themselves. While publicly embracing feel-good disarmament rhetoric, Japanese leaders have, behind closed doors, been very specific in demanding nuclear assurances from the US as Tokyo's anxiety levels about China and North Korea have ratcheted up. In Europe, fear of Russia and its nuclear threats now dominates the strategic agenda, and America's European allies now make few calls for Washington to withdraw the remaining B-61 nuclear bombs it stations there.

 

The US administration which takes office next year should not be diverted by the quixotic quest for nuclear disarmament. Nor should it take seriously equally radical ideas, such as Donald Trump's suggestion that nuclear proliferation by Japan and South Korea should actually be encouraged if those countries aren't willing to underwrite more of the cost of their own defence.

Instead, the most pressing challenge for the next US administration will be how to integrate nuclear weapons further into the political narrative and military planning of America's alliances. This challenge will be particularly urgent in our region, which is experiencing a gradual but inexorable realignment of strategic capabilities.

As the continental US becomes vulnerable to a nuclear strike from North Korea's long-range missiles, and as China enhances its ability to dominate escalation in the South and East China Seas, apprehension about America's security being 'decoupled' from the security of its Asian allies will grow. If Washington wants to convince its allies that it remains as committed as it has been in the past to intervene on their behalf, even at the cost of serious damage on the US itself, nuclear weapons cannot be taken off the table.

This has obvious implications for Japan and South Korea, both of which are locked in territorial rivalry with China and North Korea, and both of which are capable of initiating their own nuclear weapons programs. But it also has implications for a geographically remote ally like Australia, which remains concerned about the potential for further nuclear proliferation in Asia, as well as the long-term prospects of its own alliance with the US and the latter's resolve to remain strategically committed to Asia.