The crisis has been building for 13 years, since North Korea announced that it would pull out of the Nuclear Non-Proliferation Treaty — and so could use fissile material from its reactors in a weapons programme. Under the “framework agreement” brokered by the Clinton Administration, North Korea froze most parts of its weapons research in return for supplies of fuel oil. The US lifted some sanctions in place since the 1950-53 Korean War.

Clinton aides still maintain that this worked, and up to a point it did. But it froze only the plutonium-based research, and left North Korea half-free to pursue a uranium-based route.

In any case, in 2001 the Bush Administration wanted no part of a policy so much identified with President Clinton, and which it thought too wishy-washy. It refused to deal with Pyongyang other than through the six-party talks. Last year it slapped financial sanctions on North Korean businesses operated through Macau, now part of China.

That has provoked only more belligerence from North Korea. But nor has South Korea’s “sunshine policy” of engagement worked. Like China, it justified supplying North Korea with aid and fuel by saying that talking to Pyongyang was better than confrontation. Neither China nor South Korea has wanted to back North Korea into a corner, which could trigger military conflict.

Given this recent discouraging history, what now? No option is very attractive.

CUTTING OFF AID

China has already severely cut aid to North Korea; South Korea has frozen it since the July missile tests. But the world knows that the Pyongyang regime does not care about its people dying if its own grip on power is not threatened.

SANCTIONS

US firms do little business with North Korea. So the greatest pressure would have to come from its neighbours, particularly China.

But the US may try to tighten a UN resolution adopted after the July missile tests, which would press governments to stop banks and companies helping North Korea’s weapons programme, and make sure that all North Korean cargo was closely examined at its destination. The US is also likely to bar goods originally made in North Korea’s Kaesong industrial zone from a free-trade pact it is now writing with South Korea.

BLOCKADE

Any idea of a blockade is in the early stages. Under one proposal, governments might stage military exercises in waters near North Korea, under the Proliferation Security Initiative, which aims to curb the weapons aspirations of hostile countries. The patrols could have a blockade-like effect.

US TALKS

All the options above are so poor that there has been renewed speculation about whether the US might change tack and talk directly to Pyongyang, exploring a possible deal.

James Baker, Secretary of State for President Bush Sr, has said twice in the past week that he thinks the US should hold one-to-one talks with North Korea. “In my view, it’s not appeasement to talk to your enemies,” he said in an interview with ABC on Sunday.

That is a long way from the current Bush Administration’s position. But if it did want to change tack, his analysis, and pedigree, might give it political cover from the accusation that it was resorting to Clinton’s tactics.

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