North Korea collapses tunnels at nuclear test site: media reports

North Korea followed through on a pledge to blow up tunnels used for nuclear testing on Thursday, South Korean media reported, as part of steps that have reduced tension on the Korean peninsula and raised the possibility of a summit with the United States.

North Korea has conducted all six of its nuclear tests at the Punggye-ri site, which consists of tunnels dug beneath Mount Mantap in the northeast of the country.