According to the 38 North website, North Korea has already demolished several support buildings and removed some of the rails for mining carts.
Pyongyang said last week it would dismantle the site on May 23-25.
North Korean leader Kim Jong Un announced the decommissioning of the Punggye-ri site during the summit with South Korean President Moon Jae-in in late April, saying that Pyongyang’s pursuit for nuclear weapons was complete so the test site was no longer needed.
The South Korean government welcomed earlier Pyongyang’s plans to dismantle its nuclear test site. The presidential office also said that the invitation of journalists from various countries meant that the dismantlement of nuclear site would be transparent.
Pyongyang decision to close its nuclear test site has also been praised by US President Donald Trump as a “smart” move.