Speaking in Fiji on the sidelines of a forum of Pacific states, Christopher Hill said that the US was prepared to return immediately to direct dialogue with the North under the umbrella of the six-party talks process. 
 
"What we are looking for is behaviour change," Hill, who is US assistant secretary of state for East Asia, said. 
 
"We want Kim Jong Il and his government to realise there's absolutely no future on the course that they’re on and they need to switch tracks."
 
The US has insisted that all dialogue over the North Korean nuclear programme take place in the framework of multi-party talks, including Russia, China, Japan as well as the US and the two Koreas.
 
Currently, Hill said: "North Korea hasn't expressed an interest in having a dialogue with anyone."
 
Instead, he pointed to the warlike statements and threats coming from North Korea in the face of UN sanctions.
 
"It is perhaps good to remind ourselves of what kind of threatening tone that would be if they have deliverable weapons," he said.
 
‘Regime change’
 
His comments came after John Bolton, the US ambassador to the UN, said this week that the US and its allies were seeking a regime change in North Korea.
 
Interviewed by America's Fox News network on Tuesday, Bolton said that a change of government and encouraging "democratic forces" in North Korea was the "ultimate objective" of the US administration.
 
Hill's remarks appeared to be an attempt to clarify the US

“North Korea hasn’t expressed an interest in having a dialogue with anyone”

Christopher Hill, US envoy

position, and possibly ease concerns in the region that US interests in North Korea go beyond the immediate concerns over its nuclear programme.
 
China in particular sees a communist-ruled North Korea as a strategic buffer between its borders and the tens of thousands of US forces stationed in South Korea and Japan.
 
Sanctions
 
On Thursday South Korea announced that it was taking the first steps to impose UN sanctions against the North agreed after the nuclear test on October 9.
 
The announcement came a day after Pyongyang warned the South that the imposition of any sanctions would be see as a "declaration of confrontation".
 
Lee Jong Seok, the South's unification minister, said the initial measures would include a ban on the entry of North Koreans who are part of the country's nuclear weapons programme.
 
It is unclear whether any member of the North's nuclear programme has ever previously travelled to the South, although the ban could in theory be applied to key officials who take part in bilateral talks.
 
Travel between South and North Korea is already tightly regulated despite an increase in recent years in the number of South Koreans visiting the North on business and on tours.
 
Lee said that in addition to the travel ban Seoul would take other actions to meet and go beyond those mandated by the UN Security Council in response to the nuclear test.
 
Warhead designs
 
In a separate development, a South Korean defence ministry report leaked on Thursday said that North Korea was believed to have amassed up to 50kg of plutonium.
 
The report also said the North was working on designs for a small and lightweight nuclear warhead that could be mounted on a ballistic missile.
 
The briefing, compiled shortly after the recent test, said that current North Korea warhead designs weigh between two and three tonnes. To fit on a missile, they would have to weigh less than a tonne.
 
It said the plutonium could be used to build up to seven nuclear bombs.