They suggest that Pyongyang is continuing its missile work, even though it has halted test launches in what President Donald Trump and his administration have claimed as a success since his historic June meeting with North Korean leader Kim Jong Un in Singapore.
Pyongyang halted missile and nuclear bomb testing earlier this year but US and South Korean negotiators have yet to elicit from North Korea a concrete declaration of the size or scope of its weapons program me or a promise to stop deploying its existing arsenal.
"Improving relations with Pyongyang may be a laudable goal, but any claim that the North Korean nuclear and missile threats have been solved is either wishful thinking or purposefully deceptive", he said.
"There is more than enough to do in negotiating constraints on and the elimination of North Korea's nuclear and missile threats without exaggerating them and prematurely accusing Pyongyang of bad faith or calling into question President Trump's wisdom for trying nuclear diplomacy in earnest", Mr. Sigal wrote in a commentary published Tuesday by 38 North, a North Korea-focused website.
Monday's photos come just days after North Korea abruptly cancelled a meeting with Secretary of State Mike Pompeo, where the leaders were expected to discuss allowing worldwide inspectors into the country to confirm Pyongyang has begun dismantling its nuclear and missile test sites.
USA ambassador to the UN Nikki Haley, and other Trump administration officials, have repeatedly stated North Korea has done nothing to warrant the economic relief it demands.
But an official with knowledge of the North Korean position on denuclearization told me last week that the political power shift in Washington after the midterms only reinforces existing North Korean concerns that Kim's government would be left vulnerable if it agreed to denuclearize upfront, as the United States insists, only to face a politically weakened Trump administration unable to deliver on its promises. "The last round of tests under Kim Jong-un were not just coming from missile test sites". The base, located in mountainous terrain, contains a unit equipped with short-range ballistic missiles, the report said, and could house medium-range ones.
As time goes by, North Korea's likely expansion of its arsenal could force Washington to rethink its insistence on full denuclearization, said Moon Hong-sik, a research fellow at the Institute for National Security Strategy in Seoul.
Still, the CSIS report is the basis of a New York Times article accusing North Korea of deception, in the form of publicly dismantling some sites while quietly reinforcing and maintaining others.
The report says that there are barracks for members of a missile operating unit and facilities to house mobile missile launchers and other equipment.
South Korea has attempted to play down the significance of the undeclared missile sites.
"Just more Fake News", he said.
Yesterday's report about the secret sites came days after Trump said his administration is "very happy with how it's going with North Korea".
USA officials have discussed possible clandestine enrichment sites for nuclear fuel, and in July, analysts at CNS used commercial satellite imagery to conclude that North Korea was "completing a major expansion of an important factory for producing solid rocket motors for ... nuclear-armed missiles". Of 1,000 ballistic missiles North Korea is presumed to own, most are short or medium-ranged.
While US sanctions on North Korea remain in place, enforcement by traditional trading partners China and Russian Federation has relaxed since the Singapore summit, US officials have acknowledged.