A new assessment of North Korea’s nuclear program says Pyongyang appears capable of building sensitive nuclear equipment that could allow it to evade international trade sanctions and easily hide a nuclear weapons program. South Korea's Defense Ministry has said it will never accept North Korea as a nuclear state.
U.S.-based researchers analyzed photos and documents from North Korea that they say show tools and skills necessary to make gas centrifuges.
Preventing Pyongyang's access to gas centrifuges is a key aim of United Nations sanctions as they can be used to make highly enriched uranium for nuclear weapons.
Non-proliferation expert Joshua Pollack, one of the authors of the study, said if North Korea can make its own centrifuges, as evidence suggests, trade restrictions will have little effect.
"If they're making the really scarce parts, the parts that are hard to substitute for, hard to make, and hard to find, if they're making those then really the current approach of export controls and sanctions and interdiction will not help," Pollack said. "At least, it will not help as a means of denying them the technology. It seems to be too late for that. On the other hand, it may have other benefits including stopping them from exporting it."
North Korea has already produced plutonium-based nuclear bombs and tested them three times, the latest in February. The Washington-based Institute for Science and International Security
released a report in August showing North Korea doubled the size of its uranium enrichment facility at Yongbyon.
Satellite imagery of the Yongbyon Fuel Fabrication plant from July 28, 2013 showing the expansion of the gas centrifuge plant building.
Analysis of satellite images earlier this month by the U.S.-Korea Institute at Johns Hopkins also indicated the plutonium facilities had restarted.
This week it issued further analysis on images believed to show North Korea engaged in engine testing for a long-range missile.
Unlike plutonium, uranium does not give off a high heat signature, making it more difficult to track.
Pollack said it would be a serious complication for efforts to denuclearize the North.
"If we were ever to reach a denuclearization agreement with the North Koreans, it's not clear how we'll verify it. If they're able to produce centrifuges and they're able to put them, essentially anywhere, with little assurance that we'll be able to find it, how can we be confident that they're holding to their end of the bargain?"
South Korea's Ministry of Foreign Affairs on Tuesday declined to comment on Pyongyang's production of nuclear equipment.
Cho Tai-young, a ministry spokesman, said they cannot confirm issues related to intelligence. In addition, he said, they are aware that there are various opinions on North Korea’s nuclear capabilities and technologies.
Pyongyang claims the uranium program is only for peaceful energy purposes. Although centrifuges could be used to make low-enriched uranium for electricity production, on the nuclear issue, analysts note North Korea has not earned the world's trust.
This Spring it issued almost daily threats of attacks on South Korea and the United States, including nuclear war.
And although Pyongyang says it wants to negotiate an end to its nuclear programs, at the same time it has been seeking recognition as a nuclear state.
South Korea's Defense Ministry spokesman, Kim Min-seok said the government does not recognize North Korea as a nuclear state because the international community does not.
Kim said this is the most important position of the Seoul government. He added that it supports the belief that North Korea’s nuclear threats are being realized because the possibility is high that North Korea can weaponize nuclear power and actually use it. However, from a technological perspective, he says, there is no evidence to prove North Korea used nuclear weapons or is able to mount nuclear warheads on ballistic missiles.
The North's nuclear pursuits have led to tighter U.N. sanctions that are supported by its traditional ally, China.
China's Commerce Ministry on Monday published a long list of technology and materials banned for export to North Korea because of potential dual-use as weapons or for nuclear development.
Meanwhile, also on Tuesday South Korea turned down a $7.7 billion bid by aircraft maker Boeing for F-15 fighter jets.
Defense Ministry spokesman Kim cited the nuclear threat from North Korea, saying the jets were not advanced enough.
Youmi Kim in VOA's Seoul bureau contributed to this report