North Korea's Foreign Ministry announced Saturday that it will dismantle the test site between May 23 and 25.
It said several key operational support buildings, located just outside the north, west and south tunnel portals, had been razed, while some of the rails for mining carts, which had led from the tunnels to their respective spoil piles, had apparently been removed.
To provide transparency, the ministry said journalists from South Korea, the United States, China, Russia and Britain will be invited to observe the destruction of tunnels and the removal of observation and research facilities at the site.
Some analysts, citing seismological findings, have said there are signs Punggye-ri is no longer useable anyway after a tunnel collapse from the last nuclear test, though 38 North has said other tunnels remain viable to use.
The closure of the site is seen as a step toward the denuclearization of North Korea.
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. Dismantling test field may show a desire not to continue trials, but it does not imply that country is willing to deliver its nuclear arsenal.
South Korea, meanwhile, said it will hold a high-level meeting with the North Wednesday to discuss measures focusing on reducing border tensions and resuming reunions of families separated by the 1950-53 war.
Pyongyang's pledge could open the way for airlines to route flights through North Korean airspace.
After last pact between North Korea and United States, Pyongyang destroyed in 2007 cooling tower of Yongbyon nuclear power plant, where plutonium has been manufactured for its bombs. But that's most likely because North Korean officials plan to blow up those test tunnels while global journalists are in attendance later this month.
"North Korea's diplomacy has always been a repeat of hardline and appeasement", Thae said.
"The final destination that the North is headed for is not to completely dismantle its nuclear weapons program but become a nuclear weapons state covered by the paper called denuclearization", he added, according to the South's Yonhap news agency. In a tweet on Saturday, President Trump praised the North Korean leader for his "very smart and gracious gesture".
Trump and South Korea's President are due to meet May 22 at the White House.