Satellite imagery captured on June 21 reveals that North Korea continued to work on its nuclear research center after the U.S.- North Korea Singapore summit earlier in the month.

According to a report published Wednesday, 38 North, a website devoted to analysis of North Korea from the Stimson Center, said work on the site is “continuing at a rapid pace.” Judging from the images, the report noted that it appears that North Korea has modified the cooling system of its plutonium-production reactor, constructed a new building by the cooling tower, and performed additional construction at an experimental light-water reactor. The report is based on commercial satellite imagery of the Yongbyon nuclear research site taken by Airbus Defence & Space.