PUNGGYE-RI, North Korea (AP) — 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 centered on three tunnels into the underground site and a number of observation towers 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 next month.

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 the foreign media, mainly television networks, the North is apparently hoping to have images of the closing — including explosions to collapse tunnel entrances — broadcast around the world. The group included an Associated Press Television crew.

The North did not invite international inspectors to the ceremony, which limits its value as a serious concession.