BEIJING — Research by Chinese geologists suggests that the mountain above North Korea's main nuclear test site has likely collapsed, rendering it unsafe for further testing and requiring that it be monitored for any leaking radiation. In the KCNA statement, Kim said, “Every process involved with nuclear development” has been carried out, and “the means of delivery also has been conducted scientifically, resulting in the completion of nuclear weaponization.” Since the country would halt nuclear tests and stop test-firing midrange and intercontinental ballistic missiles, “accordingly, the northern nuclear test ground has ended its mission.”Kim said, according to KCNA, that “no nuclear test and intermediate-range and intercontinental ballistic rocket test-fire are necessary for the DPRK [Democratic People’s Republic of Korea] now, given that the work for mounting nuclear warheads on ballistic rockets was finished.”

 The suspension of nuclear tests could be subterfuge, but also a sign Pyongyang is serious about talks. The findings by the scientists at the University of Science and Technology of China may shed new light on North Korean President Kim Jong Un's announcement that his country was ceasing its testing program ahead of planned summit meetings with South Korean President Moon Jae-in and U.S. President Donald Trump. • Monday's report comes after North Korean leader Kim Jong Un made the announcement on April 20 that his regime would cease its nuclear and long-range missile tests and close the mountainous Punggye-ri nuclear test site, where the regime has conducted all six of its nuclear tests. Joseph Bermudez from 38 North, a Washington-based North Korea monitoring project, said North Korea's announcement of a testing freeze could be a positive step -- if it is sustained and negotiations progress.
Scientists from the University of Science and Technology of China state that North Korea's nuclear test site, the Punggye-ri Nuclear Test Site at Mount Mantap, would have collapsed just minutes after the country performed its sixth nuclear test and opened up a hole of up to 656 feet (200 m) in diameter. It has been one of the possible reasons given for North Korea agreement to suspend nuclear and missile tests.