Despite a daunting array of challenges elsewhere, US president-elect Barack Obama cannot afford to put nuclear-armed North Korea on the back-burner, analysts say.

They expect the hardline communist state to turn up the heat in coming months to test his resolve, possibly with more missile launches or even a second atomic test.

Its aim would be to renegotiate a six-nation aid-for-disarmament deal agreed in 2007, which is stalled by the North’s rejection of strict verification of its declared nuclear activities.

“These (six-nation) talks will be an early challenge for the incoming administration,” President George W. Bush’s National Security Adviser Stephen Hadley said this month.

“North Korea will test the new administration by once again trying to split the six parties (the United States, the two Koreas, China, Japan and Russia) and renegotiate the deal.”

South Korea’s state-run Institute of Foreign Affairs and National Security said Pyongyang might even stage more missile or nuclear tests to try to tame Obama’s administration or increase its own negotiating clout.

The first apparent challenge came Saturday, when the North asserted it may retain its nuclear weapons even after establishing diplomatic ties with Washington as long as it remains under a US nuclear threat.

Professor Yang Moo-Jin of the University of North Korean Studies told AFP: “North Korea is saying through these statements to Obama: ‘hey, look! We’re here with nuclear weapons in hand. Don’t look at Iran or elsewhere but at us first.'”

Hours later the North’s army General Staff stepped up the pressure.

In an unusually strongly worded statement it warned it would not allow intrusions by South Korean vessels into disputed waters in the Yellow Sea — the scene of bloody naval clashes in 1999 and 2002.

“Now that traitor Lee Myung-Bak and his group opted for confrontation… our revolutionary armed forces are compelled to take an all-out confrontational posture to shatter them,” a military spokesman said in reference to South Korea’s conservative president.

The North shocked the world with its first nuclear test in 2006 but four months later signed the denuclearisation deal.

Under the current phase of the pact it is disabling its ageing plutonium-producing plants in return for energy aid.

It has supplied information about its plutonium operation, but rejects US suspicions of a separate secret programme using highly enriched uranium.

The final phase calls for the scrapping of nuclear weapons and material in return for normalised relations with the US and a treaty formally ending the 1950-53 Korean War.

The North has also made some conciliatory gestures. A New Year message did not criticise the United States and Pyongyang even reportedly suggested sending an envoy to Obama’s inauguration, which takes place on Tuesday.

“The North Koreans will be patient and send out signals of goodwill” for the time being,” Daniel Pinkston, senior analyst with the International Crisis Group, told AFP before the latest statements from the North.

“Over the next three to six months, if there is some action or initiative from Washington that is perceived to be hostile or uncooperative, or they feel they are being ignored or disrespected, they will do something provocative.”

They could, he said, use a long-range missile to launch a satellite. A second nuclear test was also possible some time in the future.

Such pressure tactics are seen as unlikely to work.

The Democratic administration “is likely to ask for stronger verification measures than what was agreed during the Bush administration,” said Cheon Seongwhun of the Korea Institute for National Unification in a recent article.

Secretary of State-designate Hillary Clinton last week backed the six-party approach, but also indicated a greater openness to bilateral talks — apparently leaving the door open for a meeting at some point between Obama and North Korean leader Kim Jong-Il.

Some analysts believe Pyongyang, while willing to stop producing plutonium, will never hand over its bombs and seeks tacit acceptance as a nuclear power.

This, said Cheon, is something no US president could accept.

“The moment Washington decides that negotiation alone is unable to shove Pyongyang into denuclearisation, it will swiftly turn to a different approach and impose pressure on the North Korean regime on a whole new dimension,” he wrote