Satellite images from last week show movement at North Korea's main nuclear site that could be associated with the reprocessing of radioactive material into bomb fuel, a U.S. think tank said on Tuesday.
Any new reprocessing activity would underscore the failure of a second summit between U.S. President Donald Trump and North Korean leader Kim Jong Un in Hanoi in late February to make progress toward North Korea's denuclearization.
Washington's Center for Strategic and International Studies said in a report that satellite imagery of North Korea's Yongbyon nuclear site from April 12 showed five specialized railcars near its Uranium Enrichment Facility and Radiochemistry Laboratory.