SEOUL — South Korea on Wednesday prepared for a major show of military strength involving fighter jets and tanks near the tense North Korean border as Washington ruled out "feel-good" talks with Pyongyang.
The live-fire exercise, planned for Thursday with self-propelled guns and 800 soldiers, follows signs of an easing of tensions on the peninsula after the North backed down from a threat to retaliate against an earlier drill.
Although similar exercises have been held at the same firing range 20 kilometres (12 miles) south of the mainland border many times before, the latest comes with Seoul on high alert for a possible attack from the North.
South Korea's navy meanwhile began a four-day firing drill Wednesday off the east coast, a relatively distant 100 kilometres (60 miles) south of the border with the North, mobilising six warships plus helicopters.
Observers said South Korea's conservative government sees flexing its military muscles as a necessary deterrent against a fresh strike by the North.
"If you relax and are unprepared and try to be nice to the North Koreans they will never stop," said Daniel Pinkston, an expert at the International Crisis Group think-tank in Seoul. "It's like a bully in the schoolyard."
A senior South Korean military commander said Thursday's drill at the Pocheon range would "demonstrate our solid military preparedness".
"We will retaliate thoroughly if the North commits another provocative act," First Armoured Battalion commander Choo Eun-Sik told Yonhap news agency.
South Korean marines were also posted to guard a Christmas tree that was lit up Tuesday near the land border, reflecting fears that the North might fire on the display as a propaganda symbol.
Tensions have been high since the North shelled an island near the contested western maritime border last month in response to a live-fire drill by the South. The bombardment killed four people including civilians.
Seoul staged a repeat drill on the same island on Monday but the North did not go through with threats to hit back, saying it "did not feel any need to retaliate against every despicable military provocation".
The rare display of restraint eased fears of a full-blown conflict breaking out on the peninsula.
A top Chinese diplomat at the UN Security Council said hostilities between the two Koreas had come "close to fighting a war".
Pyongyang also reportedly offered nuclear concessions to visiting US politician Bill Richardson, a veteran troubleshooter, although there has been no confirmation from the North.
Seoul and Washington have expressed scepticism about the apparent overtures by the North, coming after intense sabre-rattling from Pyongyang, whose hardline communist regime is undergoing a generational power shift.
The United States said that North Korea was not even "remotely ready" to resume six-nation nuclear disarmament talks, despite the apparent concessions offered to New Mexico Governor Richardson on his private trip.
The White House made clear there was no change to US policy, despite Pyongyang's reported offer to re-admit UN nuclear inspectors, noting that the North had a record of broken promises.
"We're not going to get a table and a room and have six-party talks just for the feel-good notion of having six-party talks," said President Barack Obama's spokesman Robert Gibbs.
"When and if the North Koreans are ever serious about living up to their obligations, then we can think about restarting six-party talks."
North Korea pulled out of the nuclear talks -- which involve the two Koreas, the United States, Russia, China, and Japan -- in April 2009 and ordered UN nuclear inspectors out of the country.
It staged a second nuclear test a month later. Pyongyang's disclosure last month of an advanced uranium enrichment plant -- purportedly to serve a peaceful nuclear power programme -- heightened regional security fears.
China has called for an "urgent" resumption of the six-nation process but blocked Western attempts to condemn North Korea's island attack at the UN Security Council.