The US military chief in South Korea urged North Korea Wednesday to stop raising tensions on the divided peninsula, saying Seoul and Washington are prepared for any contingency.

"We're prepared...for any contingency, any provocation," said General Walter Sharp, referring to the US and South Korean military.

Sharp, in a speech, urged the North to "stop the provocations that have been going on, whether it is declaring all the agreements to be no longer valid or missile technology that they continue to develop."

Pyongyang announced last Friday it has scrapped agreements with South Korea on easing military tensions, a move that Washington called "distinctly not helpful."

On Sunday the communist state, which has a 1.1 million-strong military, warned of a possible armed conflict.

On Tuesday media reports said it is preparing to test-launch its longest-range missile, a Taepodong-2 with a range of 6,700 kilometres (4,150 miles), from a newly developed launch site on the west coast.

South Korean security officials, however, said Wednesday they last spotted the suspected missile on the east coast -- indicating a possible launch from the existing Musudan-ri site in the east.

A train carrying the object was last seen from a satellite at Musudan-ri, Yonhap news agency quoted an unidentified official as saying.

Officials told the agency the missile-shaped object, hidden beneath covers, had arrived by train from a military plant south of Pyongyang.

"Because of the weather conditions in the North, intelligence authorities lost track of this train for a while" before finding it at Musudan-ri, one official was quoted as saying.

The North launched two previous long-range missiles from Musudan-ri, one in 1998 and the other in 2006, sparking international condemnation.

Sharp, who commands both American forces and the combined forces command, said the US and Seoul are watching the North "very, very closely."

"We do call upon North Korea to abide by the agreements they have made in the past, which includes the complete denuclearisation of North Korea," he said.

Nuclear disarmament talks with the North, involving the US and four regional powers, are deadlocked over how its atomic disclosures should be verified.

Around 28,000 US troops are stationed in South Korea to support its 680,000-strong armed forces.

The US State Department warned North Korea Tuesday that any testing of its longest-range missile would be seen as "provocative."

earlier related report
North Korea must see cost of nuclear ambition: Hill
North Korea must "understand the true cost" of clinging to nuclear weapons ambitions, but not cut from talks, Washington's top nuclear negotiator with the country said Tuesday.

"Some people doubt the point of negotiating. They say, 'how can you talk to these terrible people?'" Christopher Hill said in an address at the Asia Society in New York.

"The format, we think, is working. The problem I think remaining is whether North Korea, taking the plutonium they've already produced, are really prepared to give up that plutonium."

Five states are involved in negotiations with North Korea -- South Korea, the United States, China, Japan and Russia.

Hill, reportedly a leading candidate to be the next US ambassador to Iraq, said North Korea must "understand the true cost" of holding on to the approximately 30 kilograms (66 pounds) of plutonium Pyongyang claims to have ready to use.

That cost, he said, includes preventing a peace treaty on the Korean peninsula and blocking access for the impoverished communist state to the global economy and development funds.

Hill criticized the North Koreans as "complete momentum killers" during six-nation negotiations aimed at dismantling the nuclear program.

But he said negotiations should be stepped up, with North Korea reassured that full disablement of its nuclear plans would open the way to bilateral talks "leading to normalization of relations."

He stressed that firmness is required with North Korea and that the five other six-party partners have a strong hand.

"I think we ought to be able to get this done," Hill said. "A country with such belligerent attitudes to its neighbors ... needs to be dealt with firmly with respect to its nuclear weapons. I just can't imagine we'd ever accept it."

Hill indicated he also favors the approach by new President Barack Obama on exploring direct talks with Iran, a sharp change of policy from his predecessor George W. Bush.

"I have found it is much better to make sure your interlocutor, sometimes your adversary, understands what your views are and I have found the best way to do this is directly," Hill said.

"It's much better to have face to face (discussion) and therefore be in their face and make them understand very clearly what you're trying to do."