Nuclear expansion

Located some 90 kilometers north of the capital Pyongyang, a huge complex dominates the landscape. The site is believed to be at the heart of North Korea's controversial nuclear program. The Yongbyon complex is North Korea's main nuclear facility, operating its first known atomic reactor. According to government data, the plant housed 2,000 centrifuges in 2010, producing low enriched uranium (LEU), reportedly to fuel an experimental light water reactor for the power-starved country.

However, the complex is also thought to have been used to produce the fissile material for North Korea's 2006 and 2009 nuclear tests. And its capacities seem to be expanding. Based on satellite imagery, the Institute for Science and International Security (ISIS) recently revealed that the building containing a gas centrifuge plant for uranium enrichment has been enlarged to twice its original size.

In a report published on August 7, the Washington-based think-tank says the expansion would allow a doubling of the number of centrifuges installed at the facility. Centrifuges are devices that are linked up in series and spin uranium in a gaseous form that can be used either to power reactors or arm nuclear weapons, depending on the degree of enrichment.

According to Phillip Schell, expert in arms control and nuclear non-proliferation at the Stockholm International Peace Research Institute (SIPRI), the technologies and materials required to produce LEU are very similar to the ones needed to produce highly enriched uranium (HEU), which can be used for military purposes. "Mostly, only the configurations of the centrifuge cascades need to be changed," he told DW.

Space for up to 4,000 centrifuges

According to the ISIS, the images provided by the satellite companies Digital Globe and Astrium Geoinformation Services indicate that work on the structure began sometime in March this year. North Korea could in theory install 2,000 more centrifuges in the site for a total of 4,000, thus enabling the production of enough weapon-grade uranium for up to two atomic weapons per year.

The research center assessed that the communist regime of Kim Jong Un could have already procured enough raw materials and equipment, many acquired from abroad, to build and install that number of centrifuges.

The report also made clear that estimating North Korea’s level of uranium enrichment capacity was "fraught with uncertainty," due the lack of information about the plant and the suspicion of other secret centrifuge sites across the country. A 2012 report by the United Nations Security Council's Panel of Experts assessed that North Korea "may run one or more parallel covert facilities capable of enriching uranium in places other than Yongbyon."

However, Gregory D. Koblentz, a Stanton Nuclear Security fellow at the Council on Foreign Relations, points out that North Korea has a history of overstating its military prowess to intimidate its enemies. He says, for instance, that North Korea has paraded mock-ups of some of its long-range missiles despite the fact that these missiles have never been flight-tested. "Building a new foundation and roof is a cheap way to make other countries think that your centrifuge program is larger and more advanced than it really is," he told DW.

The expansion of the plant may well be aimed at increasing North Korea's LEU reactor fuel production capacity. However, Schell argues that "due to the inherent dual-use nature of this technology, one cannot rule out the possibility that North Korea might already have or intends to produce weapons grade uranium for military purposes."

The ISIS report follows an announcement made by Pyongyang at the height of a surge in military tensions with South Korea. A government spokesman unveiled in April plans for "readjusting and restarting all the nuclear facilities in Yongbyon," including the ones shut down in 2007 under a six-nation aid-for-disarmament accord. The spokesman said the move was aimed at bolstering up its nuclear weapons program "both in quality and quantity."

Plutonium or uranium?

North Korea is believed to have tested plutonium devices in its first two nuclear tests. But doubts linger over the fissile materials used in the third one carried out in February 2013. Although a confirmation is yet to be provided, many experts speculate that it might be based on HEU.

Analysts point out that there are many reasons why North Korea might be switching from plutonium to uranium-based weapons. According to Karl Dewey, nuclear expert at the analytics firm IHS Jane, uranium exists in abundance in nature, making it easier to enrich in large quantities. Plutonium, on the other hand, is a by-product of nuclear reactors and more toxic than uranium. Dewey believes that such a switch would indicate that the North Koreans "could look to expand their arsenal and create a range of nuclear weapons' yields."

This view is shared by Schell: "If North Korea would decide to also develop HEU-based nuclear weapons, it would definitely open up an additional path to expand its nuclear weapons arsenal as its plutonium stockpile is believed to be limited. However, as you generally need more HEU per warhead than plutonium, an HEU design would be even more difficult to miniaturize to place atop of a ballistic missile."

A sign of 'increasing confidence'

Whatever the reason for the expansion of the building may be, Koblentz is of the opinion that this reflects North Korea’s increasing confidence in its ability to successfully enrich uranium. "Centrifuges are delicate machines and it typically takes countries several years to learn how to operate them properly. Once countries master centrifuge technology it is natural for them to expand the production capacity of their facilities."

Warnings and pleas from the international community to the isolated country have gone unheard. The UN Security Council has imposed a variety of sanctions against North Korea for its three nuclear tests and numerous missile launches, including an embargo on the import and export of nuclear and missile technology and a ban on all arms exports. The United States has also levied its own sanctions on the communist regime.

The international community is increasingly concerned about North Korea's nuclear program, as the country withdrew from the Nonproliferation Treaty in 2003 and does not allow inspectors into its nuclear facilities, making the prospect of the denuclearization of the Korean peninsula appear in even further distance.

Beijing as a key player

This is why Michael O'Hanlon, director of research for the foreign policy program at the Washington-based Brookings Institution, believes the recent discovery "will not go over well in Seoul, Tokyo and Washington." However, the expert points out that the main question remains how North Korea's major ally, China, will react. "Beijing was clearly unhappy over the nuclear test earlier this year. But it is not clear that it will object strongly here."

Nonetheless, O'Hanlon is of the opinion that "all good options involve persuading China to help the United States." He therefore advocates offering Pyongyang "a grand bargain," involving economic aid and lifting of sanctions in exchange for reforms. O'Hanlon is convinced that with that idea in place, it becomes perhaps easier to pressure North Korea for "bad behavior."

But experts warn tensions could mount this month as South Korea and the United States are set to begin a joint military exercise on August 19. Schell is of the opinion that many of North Korea's escalatory steps earlier this year can be seen as a response to US-South Korean military drills at the time, which, he says, the North viewed as a precursor for an invasion. "It would not surprise me if the exercise would result in a strong response from Pyongyang," he said.