Then, entries to the site will be blocked and all observation facilities, research institutes and guard structures will be removed.
South Korea's mass-circulation JoongAng Ilbo daily said in an editorial Monday that "it is regrettable that North Korea did not invite nuclear experts to the destruction of the test site".
In several of entrances of underground tunnels also rails that connected m with deposits of residues derived from excavations have disappeared.
Last year, US President Donald Trump and North Korea leader Kim Jong-Un were having a weird twitter war on the social media sites, exchanging threats of nuclear war.
Experts say recent commercial satellite imagery provides "definitive evidence" that North Korea has already begun dismantling its nuclear test site.
However, in spite of its pledge to stop testing, North Korea has given no indication it is willing to go beyond statements of broad conceptual support for denuclearization by unilaterally abandoning a nuclear weapons program its ruling family has seen as crucial to its survival.
"If North Korea takes bold action to quickly denuclearize, the United States is prepared to work with North Korea to achieve prosperity on the par with our South Korean friends", he said Friday.
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However less than 12 months on, he has been widely tipped to be in the move again, with Champions League finalists Real Madrid set to swoop.
And in the event Trump can secure the "complete, verifiable, irreversible denuclearization of North Korea", Pompeo said US investment could be possible, with "private sector Americans coming in" to the North to improve its energy, infrastructure, and agriculture sectors.
Analysts at the James Martin Center for Nonproliferation Studies also concluded that North Korea was taking down buildings at the test site based on satellite imagery.
The North has been vowing to pursue nuclear development unless Washington removes its 28,500 troops from South Korea and the nuclear umbrella defending South Korea and Japan.
"Those are the kind of things that, if we get what it is the President has demanded - the complete, verifiable, irreversible denuclearization of North Korea - that the American people will offer in spades". There were reports the site had collapsed and was unusable, but Kim himself reportedly dismissed those claims, saying "we have two more tunnels that are bigger than the existing ones and that they are in good condition". -North Korean summit, which Trump has said will be held June 12 in Singapore.
Seoul's Unification Ministry said Tuesday that the meeting will discuss ways to carry out peace commitments made during the inter-Korean summit.