North Korea's unpredictable regime appears to be changing tack and reaching out again to the United States, analysts say, easing fears of all-out war with South Korea after a bout of sabre-rattling.

The North's step back from the brink Monday -- after an earlier threat to retaliate against the South's live-fire drill -- helped reduce tensions on the peninsula, although the South remained on alert for possible confrontation.

Recent conciliatory gestures by Kim Jong-Il's hardline regime suggest it is "prepared for both dialogue and confrontation", said Yang Moo-Jin, a professor at the University of North Korean Studies in Seoul.

The North "wants dialogue with the United States", he added.

Unless Washington and Seoul dramatically provoke the North, such as by staging more joint naval exercises, "the chances of Pyongyang carrying out any pre-emptive attacks are pretty low at this point", he said.

Washington and its allies face a dilemma in responding to the latest round of brinkmanship by the North, which has a track record of swings between conciliatory and aggressive behaviour.

North Korea last year bolted six-nation disarmament talks and has since pursued its nuclear programme. It allegedly torpedoed a South Korean ship in March and last month shelled a civilian area, killing four people.

Reports that North Korea is willing to re-admit UN nuclear inspectors following a visit by US troubleshooter Bill Richardson may indicate it is now prioritising dialogue.

South Korea and the United States, however, reacted cautiously to the latest overtures by the secretive regime.

Washington accused the North of "broken promises". Seoul noted that Richardson's visit was unofficial and suggested it was being used by Pyongyang as political "propaganda".

North Korea in April 2009 pulled out of the nuclear disarmament talks with South Korea, the United States, China, Russia and Japan and ordered atomic inspectors out of the country. It staged its second nuclear test a month later.

The North says it wants a treaty to formally end the Korean War, as well as the lifting of sanctions, before pushing ahead with nuclear disarmament in return for badly needed economic aid.

Richardson said in Beijing on Tuesday that the North Koreans "realise that they have moved too negatively against negotiations".

"The message for the South is that Pyongyang will sidestep Seoul and only deal with Washington," said Cheong Seong-Chang, a North Korea expert at the Sejong Institute.

Pyongyang has long called for talks with Washington on signing a peace pact while the United States says this can only be discussed after the North returns to stalled nuclear disarmament talks.

Analysts say the North's regime has lived for decades in genuine fear of a US attack, especially since the Iraq invasion, and sees a peace treaty as some sort of safeguard.

The North is unlikely to try to do anything that would hamper negotiations with Washington, Cheong said.

Experts say the reclusive nation's conciliatory gestures appear to reflect its desire to avoid alienating its key ally China as well as Russia, both key players in the nuclear talks.

China blocked efforts at the UN Security Council on Sunday to condemn the North for its artillery bombardment last month.

Retaliating against the South Korean drill on Monday would have left China and Russia "in a very difficult situation", said Kim Yong-Hyun, a professor of North Korean studies at Seoul's Dongguk University.

"China and Russia can be credited for preventing the North from hitting back at the South," he said.

The island attack followed the sinking of a South Korean warship this year that has been blamed on a North Korean torpedo, and Pyongyang's surprise unveiling last month of a sophisticated uranium enrichment plant.

"North Korea is making dual approaches, leaking its intention of dialogue while also threatening," said a senior South Korean government official who spoke on condition of anonymity.

"North Korea should show us some sincerity on nuclear issues and inter-Korean co-existence," he said.

Ailing Kim is believed to see such provocations as a show of a strength to ensure a smooth power transfer to his youngest son and heir apparent Kim Jong-Un.

But "attacking the South is a luxury they can't afford at the moment", said Cheong.