A wary South Korea stayed on guard against North Korea yesterday, with jet fighters and warships deployed, a day after the communist state backed off from threats of attack over a live-fire exercise.

Washington and Seoul ex-pressed scepticism at another reported concession by Pyon-gyang – an agreement to reopen its nuclear sites to UN inspectors.

Hours after the South defied North Korea’s threats and staged Monday’s artillery exercise near the disputed sea border, the North announced it “did not feel any need to retaliate against every despicable military provocation”.

The comments eased fears of war on the peninsula, following almost a month of high tensions.

The North used a similar artillery drill on Yeonpyeong island on November 23 as a pretext to bombard the island, killing four people including civilians and damaging dozens of homes.

Pyongyang had threatened an even deadlier attack if Monday’s drill went ahead, only to change tack.

Its ally China had earlier blocked efforts at the UN Security Council to agree a statement on the crisis which would have condemned the North for its November attack.

The South’s military, accused of responding feebly to last month’s attack, said it would maintain its guard.

“This is the most serious crisis in our national defence since the (1950-53) Korean War,” Defence Minister Kim Kwan-Jin told Parliament yesterday.

“We are maintaining thorough military readiness at sea including Yeonpyeong island against possible provocations by the North,” said Mr Kim, who has promised strong retaliation using air power for any future strike.

Jet fighters were still on patrol yesterday, he said, while his ministry said warships are on standby in the Yellow Sea.

The North’s softer stance coincided with apparent concessions on its nuclear programmes to visiting US politician Bill Richardson, a veteran trouble-shooter with the North.

The New Mexico governor said it had agreed to readmit UN nuclear inspectors and to ne-gotiate the sale of fuel rods – capable of producing bomb-making plutonium – to a third party, possibly South Korea.

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