Washington’s capacity to act, of course, has been limited by the Iraq war, but that is only part of the story. American decision-makers have swung between threatening a military strike — it came close to deciding to attack in 1994 — and seeking to get other powers such as China to coax the North Koreans to the negotiating table.

What this agreement shows is the sea change that resulted from the North Korean nuclear test last year. It forced the major powers to find at least some common ground in handling North Korea. For both China and South Korea, though a covert, latent North Korean nuclear capability might be a useful counter to Japan, an openly nuclear North Korea posed a problem because it threatened to propel Japan towards militarising its own nuclear programme, something that neither Beijing nor Seoul wanted. So both have pushed hard for the deal, especially China.

The US has also compromised: it has conducted secret negotiations with North Korean officials prior to this deal, and has agreed to conduct direct negotiations with Pyongyang and normalise relations, something that the North Korean leadership had long demanded.

The question now is whether this new consensus will last. The current agreement is only a stop-gap measure: it only requires the North to freeze the programme. The real movement towards de-nuclearising North Korea will take place only during the second phase, where negotiations should be expected to be much tougher. At that stage North Korea will have to negotiate an agreement to give up not just its future nuclear weapons potential, but also any weapons or material it may already have produced.

... contd.