Seoul, South Korea (CNN) -- North Korea's latest revelations about its uranium-enrichment program confirm the country's long-term deceit, U.S. and South Korean diplomats said Monday.
The country's nuclear program was never an "if"; it was always a "when," North Korean watchers underscored.
Calling the uranium-enrichment program "provocative," Stephen Bosworth, the U.S. special envoy on North Korean denuclearization, said Monday, "That being said, this is not a crisis. We're not surprised by this."
"We have been watching and analyzing [North Korea's] aspirations to produce enriched uranium for sometime."
Those comments were echoed Monday by U.S. State Department spokesman P.J. Crowley, who said the United States believes North Korea has been seeking enrichment capability for a number of years.
While North Korea detonated plutonium-based atomic devices in 2006 and 2009, enriched uranium is generally considered a more effective material for weaponization.
The revelation of the program was made over the weekend after a visit by U.S. scientist Siegfried Hecker to North Korea, where he was shown a uranium-enrichment facility that surprised him with its advanced level of technology.
Crowley said Monday that the United States is seriously considering the information gleaned from Hecker, but cautioned that officials are still working to determine the potential implications.
Hecker got a "brief glimpse at a capability," Crowley said, adding that the United States plans to assess what that capability might represent.
Hecker, a Stanford University professor, posted a report of his November 12 visit to the North's facility in Yongbyon on the school's website Saturday.
The enrichment facility is composed of 2,000 centrifuges, according to Hecker's report.
They appear to be designed for nuclear power production, "not to boost North Korea's military capability," Hecker says.
"Nevertheless, the uranium enrichment facilities could be readily converted to produce highly enriched uranium bomb fuel," he adds.
Adm. Mike Mullen, the chairman of the U.S. Joint Chiefs of Staff, sees that as a probability.
"The assumption certainly is that they continue to head in the direction of additional nuclear weapons. And they also are known to proliferate this technology. So they're a very dangerous country," Mullen said on ABC's "This Week" program on Sunday.
Hecker's visit was the first time that North Korea has either admitted or shown off a uranium-based nuclear facility.
A senior U.S. administration official said Monday that the North Koreans were clearly expecting Hecker to report his findings to U.S. government authorities, and that they therefore "have some kind of agenda behind their decision to reveal at this time, not only what could be seen from satellite view, but also what was not visible to a satellite."
While many around the world expressed astonishment, North Korean watchers in the South were unfazed.
"This is serious, but not surprising," said. Kim Tae-woo, a senior researcher at the Korea Institute for Defense Analysis. "North Korea's history of uranium enrichment is longer than 10 years; they are revealing it at this time."
He added that all nuclear-armed states have historically pursued plutonium- and uranium-based programs.
While refusing to say whether the intelligence community knew this specific site was an enrichment facility, a senior U.S. intelligence official said Monday that North Korea's enrichment activities have been known for some time.
"American intelligence agencies have known about North Korea's uranium enrichment activities for years," the official said. "The North Koreans haven't always been particularly good, quite frankly, at concealing their intentions or capabilities."
Crowley, meanwhile, referred to the incident as a "publicity stunt that obviously we are going to evaluate further."
In 2002, then-U.S. President George Bush's envoy, James Kelly, confronted North Korean officials in Pyongyang with intelligence that the North was running a secret uranium-enrichment program. North Korea furiously denied the charges.
The subsequent tensions led to the unraveling of the 1994 "Agreed Framework," under which North Korea would hold off on its nuclear development program in exchange for light water nuclear reactors from the international community. North Korea then ramped up operations at its Yongbyon plutonium-based facility.
International agreements to shut down that project ran into difficulties with recriminations and accusations on both sides. Six-party talks to rein in the nuclear program in exchange for economic aid and diplomatic incentives have since fallen flat; the last negotiations were held in 2008.
In the lack of any clear evidence of Kelly's allegations, questions were later raised in South Korea and the United States about the veracity of the 2002 U.S. intelligence.
Experts now say that those questioners have soul-searching to do.
"I have maintained all along that they have had a program and were doing the procurement. They had blueprints from the Khan network," said Dan Pinkston of the International Crisis Group, referring to Pakistani nuclear scientist A.Q. Khan. "There is no alternative explanation; the deniers have some answering to do."
After the breakdown of six-party talks, North Korea publicly vowed in 2009 to start a uranium-enrichment program. However, the equipment shown to Hecker appears to have been imported over a significant period, Kim said.
"I think this collection of centrifuges and necessary parts may have proceeded for a long time," Kim said. "We'd better not assume they imported them at one time, but over a longer time."
As for why North Korean is revealing this now, experts point to the stranglehold of sanctions that are cutting off the regime's foreign currency sources, and suggest that Pyongyang is preparing to use the facility as a bargaining chip to obtain economic aid.
"They want food. They are starving to death. They are trying to make Seoul and Washington move. Otherwise, they are in big trouble," said Choi Jin-wook of the Korea Institute for National Unification. "And this is a transition period for the North Korean leadership; they need to provide gifts to the elite, but they don't have the resources."
Sanctions have been progressively placed on North Korea in response to a succession of nuclear and missile tests and the sinking of the South Korean warship the Cheonan in a suspected torpedo attack in March this year, at the cost of 46 South Korean sailors' lives.
Meanwhile, with national leader Kim Jong Il apparently in ailing health, his son Kim Jong Un is being raised to prominence in the isolated state, in what pundits see as a succession process.
CNN's Pam Benson contributed to this report.