North Korea must "cease" all its nuclear activities, both plutonium and uranium, before a resumption of stalled six-party talks can take place, the U.S. point man on Pyongyang said Thursday, adding that any talks with the North would be "meaningless" otherwise.

Glyn Davies, the U.S. special representative for North Korea policy, also called on Pyongyang to address the issue of Americans being detained in the communist country, among them an 85-year-old Korean War veteran from California and a Korean-American Christian missionary. Davies, however, would not confirm the detention of the American veteran, Merrill Newman.

Davies' comments after meetings in Beijing with his Chinese counterpart Wu Dawei and Chinese Foreign Minister Wang Yi come as China has been accelerating its diplomatic efforts to breathe new life into the six-nation talks that have been dormant since late 2008. The talks involved the two Koreas, the United States, China, Russia and Japan.

"It's really up to North Korea. North Korea seems not to be seriously interested in making progress on the nuclear issue," Davies told reporters at the end of his three-day visit to China and before traveling to South Korea and Japan.

"If we get back to the six-party talks," Davies said, North Korea should "cease its nuclear activities. Otherwise, I think that talks with North Korea are ultimately meaningless."

"Elimination of North Korea's nuclear establishment, both plutonium and uranium" is the key issue for the six-party talks to resume, Davies said, adding that "There are no signs of seriousness from North Korea to address the core issue."

Since conducting its third and most powerful nuclear test in February, North Korea has repeatedly expressed its willingness to reopen the six-party process "without preconditions."

South Korea and the U.S. have been demanding North Korea show its sincerity first by taking steps to denuclearize itself. China has been more accommodating toward North Korea, urging South Korea and the U.S. to lower their bar for Pyongyang to sit down at the negotiating table.

Despite the North's diplomatic overture, Pyongyang has shown no signs of abandoning its nuclear weapons. Instead, North Korea declared a so-called "Byungjin" policy of simultaneously pursuing both nuclear and economic development.

"As far as we are concerned, the 'Byungjin' is a dead end for North Korea," Davies said.

The North Korean policy "is completely inconsistent with the notion of successful six-party talks," Davies said. "So, we are calling on North Korea to take on seriously its obligations and meet its commitments and come back into the direction of the international community."

"I think, until at last they do that, it's difficult to imagine how we get back anytime soon to the six-party talks," Davies said.

Describing his discussions with Wu as "constructive and tense," Davies said, "We made some good progress."   

In a rare assessment on North Korea's nuclear capability, South Korean Defense Minister Kim Kwan-jin told lawmakers this week that the North is believed to have upgraded its nuclear program to the level that it can produce weapons-grade uranium to make a bomb on its own.

Kim's assessment is similar to that of the U.S. and other allies. In late 2010, North Korea showed off a previously undetected uranium enrichment facility to a visiting U.S. nuclear scientist, confirming suspicions that Pyongyang is on its way to creating a second source of weapons-grade nuclear material.   

"We evaluate that North Korea can build a nuclear weapon using uranium," Kim said in testimony before the National Assembly.   

Meanwhile, regarding the issue of Americans in North Korea, Davies said he had seen reports of the 85-year-old Newman having been detained by North Korean authorities for about three weeks.

The other American being detained in the isolated country is Kenneth Bae, a Christian missionary who was captured in North Korea more than a year ago.

Newman is a Korean War veteran from Palo Alto, California, who traveled to the North on a tourist visa. 

Davies said he could not comment on the issue because of the U.S. Privacy Act, but added that Washington is "working very hard" through the Swedish Embassy in Pyongyang "to try to move this issue along," without naming Newman by name.

Asked whether the detained Americans would affect diplomatic efforts to resume the six-party talks, Davies replied, "It is an indication that North Korea seems not to be seeking a better relationship with the United States. They are not taking actions to address our concerns."

(Yonhap News)