In a highly provocative snub to Washington, Beijing and Seoul, North Korea has broken the United Nations seals that had disabled its nuclear programme, and said it would soon begin feeding atomic material back into its Yongbyon facility.

As well as kicking UN nuclear watchdog inspectors out of the country and re-opening its reprocessing plant, Pyongyang is now likely to demand the removal of International Atomic Energy Agency (IAEA) seals on the thousands of plutonium fuel rods removed from the plant last year.

The fuel rods represent the most critical ingredient in the resurrection of Kim Jong Il’s nuclear weapons programme – a scenario which the United States and North Korea’s immediate neighbours thought they had negotiated off the table and are desperate to avoid.

The sudden policy reverse by Pyongyang also comes amid swirling doubts over the health of North Korea’s enigmatic and unpredictable dictator.

Kim’s non-appearance at a series of high profile public events in North Korea has triggered speculation that the “Dear Leader” of the nuclear-armed communist country may be extremely ill, incapacitated or even dead.

Defence analysts in Washington and Seoul have begun to question how far the sudden shift in North Korea’s behaviour reflects a change in power structures beneath the regime’s opaque surface.

On Monday, the US assistant secretary of state and chief nuclear negotiator with Pyongyang, Christopher Hill, openly speculated that the regime’s tougher line in the past month clearly corresponded to the reported failure of Kim’s health.

The restarting of North Korea’s nuclear programme follows threats from Pyongyang last week that it would abandon the so-called Six Party Talks – a series of prickly negotiations between the two Koreas, the US, Japan, China and Russia that have frequently collapsed.

Despite the many diplomatic frustrations of the process, though, it did appear last year that progress was being made: as well as agreeing to dismantle its nuclear programme in exchange for aid, and allowing IAEA inspectors to monitor the shutdown, Pyongyang broadcast images of the controlled detonation of an old cooling tower.

But yesterday’s potentially incendiary move sets the entire progress of disarmament talks back at square one and comes amid growing toxicity of relations between North Korea and the outside world.

A major contributor to the tensions surrounding the nuclear programme has been the continued designation of North Korea by the US as a sponsor of terrorism.

North Korea appeared on the brink of leaving the list, but over the summer, the US negotiators adopted a harder line. In an increasingly tense rhetorical climate, Pyongyang then declared that it no longer cared whether or not it was on the list, depriving Washington of one of its few bargaining chips.

Analysts in Seoul said that the restarting of Yongbyon, which would take at least 12 months to complete, would provide the North with a useful bargaining tool as the issues of Kim’s health – and the still unanswered question over who might succeed him – came more fully to light. With the plant partially re-started, North Korea might expect to win further concessions or aid as it struggles with massive food and energy shortages ahead of the notoriously bitter Korean winter.

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