"North Korea Appears to Be Rebuilding Tunnels at Closed Nuclear Testing Facility" by Hyemin Son for Radio Free Asia

Radio free Asia cited ONN reporting on the expansion of the Punggye-ri nuclear site.

RFA reporting recently cited ONN's Update: Developments at the DPRK's Punggye-Ri Nuclear Test Site between 24 March and 6 April 2022.

"The Open Nuclear Network (ONN), a non-profit organization headquartered in Vienna, Austria, reported last week that North Korea is believed to have built an entrance to tunnel 3, south of the Punggye-ri nuclear test site. The ONN report was based on satellite imagery taken between March 24 and April 6."