Photo: The Canadian Press

This Wednesday, May 23, 2018 satellite file image provided by DigitalGlobe, shows the Punggye-ri test site in North Korea.

North Korea carried out what it said is the demolition of its nuclear test site Thursday, setting off a series of explosions over several hours in the presence of foreign journalists.

The explosions at the nuclear test site deep in the mountains of the North's sparsely populated northeast were centred on three tunnels at the underground site and a number of buildings in the surrounding area.

The planned closing was previously announced by leader Kim Jong Un ahead of his planned summit with U.S. President Donald Trump, which is scheduled to take place next month.

The demolition came as the North lobbed another verbal salvo at Washington, calling Vice-President Mike Pence a "political dummy" and saying it is just as ready to meet in a nuclear confrontation as at the negotiating table.

The North's decision to close the Punggye-ri nuclear test site has generally been seen as a welcome gesture by Kim to set a positive tone ahead of the summit. Even so, it is not an irreversible move and would need to be followed by many more significant measures to meet Trump's demands for real denuclearization.

By bringing in a small group of television journalists and other members of the news media, the North is likely hoping to have dramatic images of the closing — including explosions to collapse tunnel entrances — broadcast around the world.

The group of journalists that witnessed the demolition included an Associated Press Television crew.

The North did not invite international nuclear weapons inspectors to the ceremony.

The summit plan has hit a number of speed bumps recently as both sides have begun trading barbs and taking tougher positions. Trump met with South Korean President Moon Jae-in on Tuesday at the White House for consultations and suggested the summit could be delayed or even called off entirely.

Even so, both sides still seem to want to hold the meeting, which would be unprecedented.

Success in talks would be a huge accomplishment for Trump. Meeting with the U.S. president as an equal on the world stage would be a major coup for Kim.