The US ambassador to Seoul said on Wednesday that he expects North Korea to disable its nuclear plants by year-end, but getting it to give up atomic weapons which it already possesses will be tougher.
Alexander Vershbow was speaking to YTN cable news television as a group of US, Chinese and Russian nuclear experts was visiting the communist state to advise on disablement methods.
The North has shut down its Yongbyon complex under a six-nation February deal, and the next step is to declare and disable all nuclear programmes.
"I think that the context we've had, and reports we've had from other participants with direct exchanges with North Korea, give us a reasonable degree of confidence that the current stage will be completed successfully by the end of this year," Vershbow said.
Despite general optimism about the process, the US envoy remained cautious about the coming stages.
"The six-party talks will enhance the chances for greater peace on the Korean peninsula, while recognising the big challenge -- actually getting rid of nuclear weapons and eliminating the nuclear programmes -- still lies ahead as a challenge for 2008," Vershbow said.
The two Koreas, the United States, China, Russia and Japan are members of the six-party process.
North Korea has said it will disable its programmes by year-end in exchange for economic, security and diplomatic benefits.
But the February agreement does not specifically mention any existing nuclear weapons or plutonium stockpiles held by the North, which conducted its first atomic bomb test last October.s
The North has enough plutonium to build about five to 12 nuclear weapons, according to various estimates.