North Korea has likely mastered the technology for arming its missiles with nuclear warheads, a former US intelligence official said Friday.

"The fact that they have a warhead that's fitable to the Rodong (ballistic missile) is pretty much given," said Arthur Brown, who until 2005 was National Intelligence Officer for East Asia at the US Central Intelligence Agency (CIA).

"We (the United States) went from nothing to missile capable in seven years. The Russians went from their first test to missile capable in six... Why do we think the North Koreans can't have that kind of technology?"

What was unclear was how much uranium and, or, plutonium North Korea possessed and how much they need for each of their weapons, he told a press conference at the Foreign Correspondents' Club of Japan.

"If we knew these two numbers then we could run the maths and say how many weapons they actually have," said Brown, who did not disclose his sources and said it was tough to get accurate information.

North Korea, which tested a nuclear weapon for the first time two years ago, said this week it would start work to resume plutonium reprocessing at its Yongbyon complex, possibly within a week.

The standoff comes amid reports that North Korean leader Kim Jong-Il suffered a stroke around mid-August.

"It was a serious stroke," said Brown. "It's not a light stroke. He has recovered a bit but I think no one expects him to come back into a full recovery mode at this stage."

earlier related report
US nuclear envoy to visit Korean peninsula: official Top US nuclear envoy Christopher Hill will visit Korea this week for talks in Seoul over the deadlocked disarmament deal on North Korea, an official said Sunday.

Hill was expected in Seoul on Tuesday to meet with his South Korean counterpart Kim Sook to discuss "concerns" about North Korea, a senior foreign ministry official said on condition of anonymity.

The US envoy's trip comes after the communist North announced moves to restart its plutonium-producing plants.

The Washington Post, citing unnamed sources, said Sunday the US envoy was planning to travel to North Korea as well in a last-ditch effort to salvage the faltering accord to end Pyongyang's nuclear weapons programmes.

"His further travel plan will be confirmed by the US," the Seoul official said, responding to the Post report.

earlier related report
NKorea nuke talks may be close to breakdown: Skorea
International nuclear disarmament talks with North Korea may be near breakdown after the communist state announced moves to restart its atomic plants, South Korea's foreign minister warned Friday.

Speaking to reporters, Yu Myung-Hwan said the North's tactics may be linked to the upcoming US presidential election.

"We are at a difficult situation where we may be going back to square one," he admitted.

Yu's comments came after North Korea earlier this week announced it would start work to resume plutonium reprocessing at its Yongbyon complex, possibly within a week.

That appears to have brought a six-nation aid-for-disarmament agreement -- negotiated after the hardline Pyongyang regime tested a nuclear weapon for the first time two years ago -- close to collapse.

International Atomic Energy Agency (IAEA) inspectors have been barred from the reprocessing plant, which produces the raw material for nuclear weapons.

Yu said the North's move may be a strategy to capitalise on the political situation in the United States, where Republicans and Democrats are locked in campaigning for the Novembeer 4 presidential election.

"It is possible that the North's decision to go back on the disablement steps is a strategy associated with the US presidential election," Yu added.

He was speaking on his return from a US trip during which he met Secretary of State Condoleezza Rice and Chinese Foreign Minister Yang Jiechi.

Japan and Russia are also members of the six-party forum along with the two Koreas.

Some analysts say the North may feel this is a good time to demand nuclear concessions, with a "lame-duck" president in Washington and the United States focused on the election and the financial turmoil in Wall Street.

Yu said the North should realise "that it is impossible, as long as it tries to be a nuclear state, to get the help of international financial institutions and trade with other countries and get investment."

Following the landmark agreement in February 2007, North Korea in July 2007 shut down Yongbyon under IAEA supervision.

Four months later, it began disabling the complex, and in June this year it handed over details of its plutonium-based nuclear programme, thought to have produced enough material for about six bombs before the shutdown.

In return, it was promised one million tonnes of fuel oil or the equivalent energy aid as well as diplomatic concessions, including its removal from a US terrorism blacklist which blocks some foreign aid.

But Washington refuses to delist the North until it agrees procedures for strict verification of its nuclear disclosures, prompting Pyongyang to restart its plutonium programme.

Yu acknowledged that the need for a verification protocol before delisting was not specified in written agreements. But he said "the US and North Korea had an understanding on this point."

Washington said Thursday the verification conditions were not a burden and urged the North to pull back from relaunching its weapons programme.

"What we're asking for is basically a standard verification package," said State Department spokesman Robert Wood. "It's not something onerous, it's not something that hasn't been done in the past.

China's foreign ministry Thursday urged all parties to "display flexibility to solve the verification issue."