A missile launch pad along the western coast of North Korea as well as a nuclear test site in Punggye-ri are being refurbished for use again.
Satellite photos of North Korea's missile launch pad in Tongchang-ri taken on Dec. 7, when the North announced it had conducted a "very important test," were virtually identical to one taken in July 2018, before promised dismantlement began.
During his summit with U.S. President Donald Trump in Singapore in June of last year, North Korean leader Kim Jong-un pledged to shut down the test site and actually dismantled a mobile structure and a testing facility nearby.
But the North began rebuilding the facility after a second summit with Trump in February this year collapsed, and the facility is now ready for use.
Nick Hansen, a military expert at Stanford University, told VOA that North Korea probably stored the parts in order to reassemble them later.
The website 38 North at Johns Hopkins University, meanwhile, said satellite images show the "presence of vehicle tracks in the snow cover" at the Punggye-ri nuclear test facility, which North Korea dramatically blew up in May 2018.
A satellite photo of the facility taken on Nov. 18 shows no vehicles or personnel. But another picture from last week shows vehicle tracks and human footprints in the snow that lead to a "small assembly area."
"The precise nature of this latest activity is unclear, but does suggest, at the very least, that personnel remain onsite at the complex," it said.