The regime could use threats of nuclear attack to intimidate Tokyo to preclude US. Pyongyang could use the fear of nuclear weapons to coerce South Korea to accommodate North Korean demands that it for example end bilateral military exercises and reduce US. Mysterious North Korea Site May Be Building Nuclear Bomb Parts Report Says South China Morning Post North Korea is undertaking construction work at its main nuclear weapons test site for the first time in about four years according to an analysis of satellite imagery raising fresh security concerns as South Korea elects a new leader. . Images captured Friday show very early signs of activity at the mountainous area of Punggye-ri including the construction of a. North Korea has test-fired a range of increasingly powerful missiles this year and officials in Seoul and Washington fear it may be preparing to. It conducted six nuclear weapons tests in tunnels at the site from 2006 to 2017.