Recent tunneling activity at North Korea's nuclear testing grounds suggests that Pyongyang is preparing for more trial explosions sometime in the future, according to a new image analysis.
Commercial satellite photographs taken on May 13 around the "West Portal" area of the North's Punggye-ri test site show significant digging, according to Joel Wit, who edits the 38 North Website documenting developments in the isolated country.
Speaking on Tuesday to an audience at the American Security Project, Wit said another underground test is not likely in the short term but the preparations appear to indicate Kim Jong Un's regime is keeping its future options open.
The activities are open to interpretation. North Korea could be launching construction of a new tunnel, completing a tunnel already under way, repairing damage to an existing tunnel or clearing debris from older underground chambers, he said.
All of those options, though, suggest that Pyongyang is "conducting long-term projects … that may be necessary for the conduct of future tests," according to a new image analysis report by 38 North. To date, there have been three underground nuclear tests at Punggye-ri, the most recent happening in February.
"I am not saying that there is going to be a nuclear test tomorrow. It doesn't look like this is preparations for the near term. It looks like this is more of a long-term effort," said Wit, a former State Department official who, in the 1990s, oversaw implementation of an ultimately unsuccessful bid to end the North's nuclear weapons work.
Evidence of North Korea's tunneling effort can be seen in satellite imagery of piles of mountain rock near the West Portal and cart rails installed to haul away the debris, according to the analysis.
The tunneling work currently taking place is substantial. Tailings dumped on the ground are gray in color and thus determined to be rock "coming out of the mountain" rather than simply surface soil, Wit said.
Photographs taken on June 1 reveal a significant new tailings site sandwiched between the West Portal and an older dumping grounds, according to the 38 North report.
North Korea is also busily working on reopening its disabled plutonium production reactor at the Yongbyon nuclear complex. The five-megawatt Soviet-era reactor was mothballed and its cooling tower blown up under a 2007 denuclearization accord with Washington.
The North declared in April it would reopen the facility and rededicate it to the production of fissile material for its nuclear weapons program.
To save time in getting the reactor operational, rather than construct an entire new cooling tower, the North apparently plans to use the cooling system it has built for a newer experimental light-water reactor at Yongbyon to also provide services to the older plutonium reactor, Wit said.
"They are not rebuilding the cooling tower. That would take them probably longer than what they are doing," he said. "They are constructing a cooling system, [and] hooking up the five-megawatt reactor to the pump house they've already built for the light-water reactor."
This shows that "like any good organization, the North Korean nuclear scientists had a contingency plan for restarting the five-megawatt reactor," said Wit.
His website earlier this month said the deactivated reactor could be operational sometime later this summer, but its ability to produce more plutonium would depend on having enough usable fuel rods.
Pyongyang is understood to possess a quantity of fuel rods that were designed for use in a 50-megawatt reactor. Because work on the reactor was never completed due to the 1990s Agreed Framework with the United States, the fuel rods fell into disrepair, according to Wit. The fuel rods would have to be "retooled" before they can be installed into the five-megawatt reactor.
"If you think that they had a contingency plan in place [for restarting the reactor], then you have to believe they had a plan for retooling the fuel rods," he said. "But I don't know. We have no evidence one way or the other."