Iran's Supreme Leader Ayatollah Khamenei in 2004.

Stand-off ... Iran's Supreme Leader, Ayatollah Khamenei, presides over a criminal state. Photo: AP

The first war of 2013 - Israel's attack on Iran - is threatened for ''spring or early summer'', the time by which the Israeli Prime Minister, Benjamin Netanyahu, who is likely to be re-elected next month, believes that the Mullahs will be ''nuclear weapons capable''. The White House may prevail upon him to postpone until Mahmoud Ahmadinejad is replaced in June, but his successor as president will just be another proxy for the international criminal who really rules Iran - its Supreme Leader, Ali Khamenei.

The US President, Barack Obama, has promised that a US-led coalition will prevent Iran from obtaining the bomb, and when a US president talks of ''coalition'' he generally means Britain and Australia.

Will next year see the West drift into another bloody Middle East engagement? The evidence that Iran's theocratic government wants the bomb is compelling and it could choose to manufacture several over the next few years. It is a criminal state - given under Khamenei's rule to killing those who disagree with its politics or religion. He was the president in 1988 when his death squads entered Iran's jails to execute some 7000 Marxist, atheist and Islamic non-conformists. Mainly students who had been imprisoned for protesting or pamphleteering, these victims were buried in mass graves at which their families are still not permitted to mourn.

Israeli Prime Minister Benjamin Netanyahu shows an illustration as he describes his concerns over Iran's nuclear ambitions in 2007.

Iran's pursuit of a nuclear capability is increasing anxiety for Israel's Prime Minister, Benjamin Netanyahu. Photo: AP

Later, as Supreme Leader, Khamenei issued orders to assassinate hundreds of the regime's overseas enemies (the author Salman Rushdie was one who got away) and to blow up a synagogue and community centre in Buenos Aires. In 2009 he unleashed the militia that tortured and killed many Green Movement protesters.

The prospect of this merciless mass murderer obtaining nuclear weapons is certainly alarming - but does Israel, even if backed by a US-led coalition, have any right to stop him? Israel and its allies are entitled to attack an enemy in self-defence under Article 51 of the United Nations Charter but only if an attack from that country is ''imminent'' - meaning that the onslaught must be about to happen.

Over Iraq, George W. Bush and his bush lawyers tried to develop a doctrine of ''pre-emptive self defence'', namely the right of the US to invade any nation that might one day have the weapons to threaten the US - but this doctrine has no place in international law. Iran will not actually have a bomb in 2013 (even if it manages to enrich its uranium to weapons-grade, it will still take time to weaponise and to develop a delivery system), so a strike on its nuclear facilities in 2013 would be flagrantly unlawful.

It would also be irresponsible. Supporters of Israel assume it will be a ''surgical strike'' such as the one on Osirak, the Iraqi facility that Israel bombed in 1981 with few casualties. But Natanz - a prime target in any strike on Iran because it is where most of its centrifuges are whirring to enrich uranium - employs 5000 workers around the clock. The other potential targets store 371 tons of uranium hexafluoride, so bombing them would set off a toxic cloud that could asphyxiate thousands if the wind were to blow in the wrong direction. The attack would prompt reprisals - rockets on Israel from Hezbollah and doubtless Iran would close or mine the strait of Hormuz and attack US naval vessels there: a wider war might follow.

The flaw in the argument for attacking Iran is that nuclear capability does not mean nuclear culpability. While Ahmadinejad is a vicious anti-Semite, Iran has no quarrel with its own Jewish population and although its leaders are fond of imagining a world without Israel, they are referring to millennialist prophecies about wiping all unbelievers from the map, and are not planning to drop a nuclear bomb on Tel Aviv.

The Mullahs are at least as rational as a gang of serial killers and are well aware that Israel itself has 200 nukes, some on submarines stooging the eastern Mediterranean, which would be shot at Tehran in immediate reprisal for any attack. The real danger of Iran's acquisition of nuclear weapons is that the ruling Mullahs will be invincible and proliferation will follow throughout the Middle East.

Saudi Arabia is already negotiating ''off the peg'' atom bombs from Pakistan and the Muslim Brotherhood has long had a policy to obtain nuclear weapons for Egypt. The UN has cancelled this month's long-awaited conference in Helsinki on the subject of ''a nuclear-free Middle East'', for the very good reason that the Middle East will soon be nuclear-full.

While Australia must be careful not to be drawn into another unlawful war in that region, the most urgent problem of nuclear proliferation lies closer to home. North Korea is believed to have made 12 bombs so far, each many times more powerful than the device that flattened Hiroshima.

Its recent ballistic rocket test was successful: once it works out how to fit a nuclear warhead and to prevent that warhead from exploding when it re-enters the earth's atmosphere, this uncontrollable country and its unpredictable dictator will be able to deliver a nuclear bomb to California or Sydney or to those American bases planned for Darwin and the Cocos Islands, which may themselves harbour nuclear arms. North Korea may not be as big or as brutal as Iran, but not long ago it sank a South Korean corvette with the loss of 46 young lives, while China - which voted in the Security Council to condemn the latest ballistic test - can no longer exercise control over this impossible state.

The fact is that we are entering a new era of nuclear proliferation so dangerous that we may soon be nostalgic for the Cold War.

Then, bombs were kept under tight security and the five nations that possessed them were run by men with children, retirement plans and no wish for Armageddon (when the Cuban missile crisis came, it was solved by a rational deal: the US promised to withdraw its nukes from Turkey, in return for Khrushchev pulling his nuclear-tipped rockets out of Cuba). The supreme leaders of North Korea and Iran are not men of the same mould and Pakistan under any leadership will remain insecure.

It already has 110 nukes, some kept at Minhas air force base, which Islamic jihadists attacked in August. They were beaten back, but there will be a next time: proliferation makes both nuclear accident and terrorist acquisition much more likely. The fact that we have not had a bomb dropped in anger since Nagasaki, more than 67 years ago, seems to have induced a complacency that can no longer continue.

Proliferation is here to stay and Obama's promise of ''a world without nukes'', which won him the Nobel peace prize in 2009, now seems fraudulent. Ironically, international law has managed to outlaw the poisoned arrow and the dum-dum bullet, the landmine and the cluster bomb, but nuclear weapons have thus far been too hot for it to handle. It is plain that their use is a breach of the law of war: their ionising radiation cannot distinguish between soldier and civilian, military target and hospital or school. They cause disproportionate suffering and they pose an existential threat to the environment. Even a limited war, for example between India (which has 100 nukes) and Pakistan over Kashmir or between North Korea and the US, would probably change the climate before climate change.

But how is the problem of proliferation to be addressed, short of opportunistic use of force by the US and its allies on countries such as Iran? Many states (the movement is led by Mexico and has not yet been joined by Australia) plan to make the acquisition of nuclear weapons a crime against humanity by amending the Treaty of the International Criminal Court at its review conference in 2016. That would entitle the Security Council to authorise an attack on Iran or any other country outside the nine that already possess nuclear weapons to stop it from assembling a bomb.

But this will have to be accompanied by a binding agreement between the nuclear-armed states gradually to reduce the number of nukes in their arsenals to zero and by the establishment of a powerful UN inspection agency to replace the toothless International Atomic Energy Agency, which cannot inspect suspicious facilities, in Iran or elsewhere, without the permission of the suspect state.

Whether children will live in a world without nukes depends on whether the international community can be made sufficiently fearful of a nuclear war to reach an agreement on gradual but complete disarmament. If there is a silver lining in the mushroom cloud hypothetically hovering over the Middle East, it is that the prospect of merciless Mullahs with fingers on nuclear triggers will frighten the world sufficiently to produce and enforce a law to ban the bomb.

Geoffrey Robertson, QC, is the author of Mullahs Without Mercy: Human Rights and Nuclear Weapons, Vintage, RRP $34.95.