Iran and North Korea are likely to be topics in Tuesday night's debate between the vice-presidential candidates. They were also at the centre of last week's presidential debate. Indeed, the only thing both candidates agreed on last week - aside from the quality of each other's parenting - was the threat of nuclear proliferation. George W. Bush pronounced mullah "MOO-lah"; Democratic challenger John Kerry lacked time to present detailed proposals. Still, the positions of the two sides on this crucial issue are already clear. A review shows the "unilateralist" Republicans are offering the stronger - even the more multilateralist - policy.

Start with North Korea. Mr Kerry charges that the US has done nothing to stop Pyongyang arming itself. As a result, Mr Kerry said last week, North Korea has "gotten nuclear weapons". Mr Kerry would, therefore, like the US to initiate direct (one could say, unilateral) talks with North Korea.

As vice-president Dick Cheney is likely to explain on Tuesday, the Democrats' arguments are wrong on two counts. The first argument is that North Korea's nuclear weapons are the result of Bush policy. The North Koreans have been moving towards a weapons programme and covertly enriching uranium since the Clinton days. The Clinton administration took great pains to lock North Korea into a commitment not to turn a fuel capacity into a military one but North Korea ignored it. As for the Bush administration, it has worked hard on North Korea from the start, participating in a six-nation discussion that includes China. The US does not have much influence over North Korea, which is probably one reason Pyongyang felt it could floutMr Clinton. But China does - it provides 80 per cent of North Korea's energy in subsidised coal and diesel fuel. This, as Mr Cheney could point out, is one reason the president hosted Jiang Zemin in Crawford, Texas, two years ago.

Then there is Iran and its troubling uranium enrichment, which John Edwards will probably bring up. He has already blamed the Bush administration for allowing "dangers to mount" - that is, allowing nuclear weapons to be developed.

Mr Kerry also alleges that the US has no Iran plan. Last week he said the UK, Germany and France "were the ones who initiated an effort, without the US regrettably, to curb nuclear possibilities in Iran". He argued that the Iran situation would not be worsening had the US offered nuclear fuel to Iran and supervised its nuclear fuel plants. Then if Iran had diverted material to nuclear weapons the US could have punished it with sanctions.

The first rebuttal here is that, as Mr Bush noted, the US has approved of and supported the European initiative at issue from the beginning. The administration does not necessarily agree with this plan. But it has gone along, doubtless because ally Tony Blair wants it to.

The second point is more fundamental: with or without supervision, providing nuclear fuel to Iran is a crazy idea. Iran does not need a fuel source in the way North Korea does. It has oil and natural gas. The only reason Iran would want to build its nuclear capabilities is to create a weapons programme, or at least the potential for one. And, as Mr Bush noted, those theoretical US trade sanctions against Iran to which Mr Kerry referred are already real, and in place. They predate this administration.

Finally, the US has been aggressively working on the Iran problem through a traditional multilateral venue, the International Atomic Energy Agency. Now is the moment to refer the issue of a weapons programme to the United Nations Security Council, with the expectation of pursuing international sanctions on Iran. France, Germany and Britain have, however, been unwilling to make the difficult decision to join the US in this push.

What about nuclear challenges beyond Korea and Iran? The US and its allies have spent enormous energy preventing technology transfer: the sale of nuclear toolkits via the black market. This Proliferation Security Initiative includes more than 60 nations. An aggressive PSI interdiction at sea helped convince Libya's Muammer Gadaffi to give up his programmes for weapons of mass destruction. Mr Cheney recently explained his administration's attitude to multilateralism: the US, he said, wants to work multilaterally. But being multilateralist does not mean "submitting to the objections of a few". And multilateralism does not preclude Mr Bush's stated policy of staying "on the offence". In brief, what Democrats are asking for is a return to the emphasis on careful diplomacy that was the policy of the US in Asia and the Middle East during the 1990s. This is why Mr Kerry recalled Mr Bush's father, in the debate.

But the reality is that the look-away-and-pre-empt-not policy of the Bush-Clinton 1990s did damage. It is a "colossal error" - to borrow a Kerry phrase - to give countries such as Iran and North Korea time to develop nuclear weapons. Diplomacy, as Colin Powell, US secretary of state, said recently of Iran, doesn't have to "mean pretending something isn't there when it is there". In this new and unstable era, both diplomacy and offensive action have their place. Right now the Republicans are the ones showing they are ready to try both.

© Copyright 2004 Financial Times