Experts remain skeptical whether North Korea is serious about giving up its nuclear weapons, noting that Kim announced on January 1 that the country has completed its nuclear force, calling it a "powerful deterrence" against threats from the United States.
N Korea said it will "completely" destroy Punggye-ri test site, in a ceremony scheduled between May 23-25 in front of invited foreign media.
The pictures, taken on 7 May, are "the first definitive evidence that dismantlement of the test site was already well underway", according to a blog post by 38 North, a website run by former USA diplomats.
The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), the worldwide organization that keeps watch for nuclear tests, said it has yet to be invited to observe the dismantlement, Radio Free Asia reported Tuesday.
Some experts saw this as a slight but significant moving of the goal posts when it comes to the Trump-Kim summit.
A decade ago, the last time North Korea took talks with the U.S.so far, then-leader Kim Jong Il blew up a cooling tower at the Yongbyon nuclear plant as part of a deal to limit its weapons program.
The site's closure would set up next month's historic summit between North Korean leader Kim Jong Un and President Donald Trump, which is shaping up to be a crucial moment in the global diplomatic push to resolve the nuclear standoff with the North. The southern and western portals could still support detonations, even if the northern side was badly damaged over the five nuclear tests conducted there, 38 North said April 30.
The reclusive state also released three U.S. citizens imprisoned in North Korea as newly confirmed Secretary of State Mike Pompeo visited Pyongyang for a second time last week to prepare for Donald Trump's upcoming summit.
Not everyone shared the optimism over Pyongyang's nuclear pledge.
The South Korean government, which had expected North Korea to invite nuclear experts and global watchdogs for the shutdown process, said it remains to be seen whether Pyongyang maintains its stance. Last month, President Trump called the North's decision to suspend missile and nuclear tests "very good news".
Thae emphasized that Kim would demand an assurance of safety against any attacks on North Korea by other countries in return of denuclearisation. North Korea is desperately in need of energy ... for their people.
The two Koreas are due to meet for a high-level meeting on Wednesday to discuss follow-up measures from their summit last month, Seoul's unification ministry said.
The shutdown process will unfold under the presences of journalists, including those from the US and South Korea.