Satellite imagery taken Thursday — just a day before North Korea kicked off a key summit of the country's ruling party — shows that Pyongyang may be preparing to conduct its fifth nuclear test "in the near future," a U.S. think tank said Friday.
The website 38 North, run by Johns Hopkins University's School of Advanced International Studies, said that the imagery showed rare movement at what is believed to be the command center of the Punggye-ri nuclear test site.
"While the historical record is incomplete, it appears that vehicles are not often seen there except during preparations for a test," the website said.