North Korean leader Kim Jong-un has promised to tear down the country’s only known nuclear test site later this month. All six of Pyongyang’s nuclear tests have been carried out at the top-secret Punggye-ri site, which is beneath a mountain in the north-east of the country, near the Chinese border.
The North said on Saturday that it would hold a ceremony for the dismantling of the facility between May 23-25, with foreign media invited to attend.
There has been increasing pressure on Pyongyang to give up its nuclear weapons ahead of the meeting between Kim and US President Donald Trump on June 12.
The mountains in the north-eastern the province of North Hamgyong are said to be an ideal location for the test site, able to withstand powerful nuclear blasts.
The site’s existence became known in 2006 when the North conducted its first nuclear test under Kim’s late father, Kim Jong Il.
Activities have been closely watched through satellite imagery since then.
The North’s nuclear programme has progressed rapidly in recent years. Since Kim took power in 2011, there have already been four atomic tests.
Its most recent test last September produced an estimated yield of as much as 250 kilotons – an explosion 16 times more powerful than the US atomic bomb dropped on Hiroshima in 1945.
But Punggye-ri’s proximity to China has started to worry Beijing, as the tremor from the sixth test was felt across the border and caused many residents to leave their homes in panic.
Some critics have suggested that the site is already old and damaged, and that the promised dismantling is an empty gesture.
A recent study on by seismologists on the mainland suggested rock had collapsed under the mountain, making it unusable.
Jeffrey Lewis of the Middlebury Institute of Strategic Studies in the US dismissed the claims, saying there is “no basis” to conclude it is no longer usable and the promised closure is “not a case of passing off damaged goods”.
There have also been concerns that the site poses a major radioactive threat to the wider region.
The North claims its nuclear tests are safe. But some South Korean and Japanese media reported that workers at the site or residents from the area had been exposed to radiation, and suffered symptoms including cancer and the births of deformed babies.
Seoul ran medical checkups on 30 defectors who came from the region for potential radioactive exposure last year.
Four of them showed symptoms that could be attributed to radiation exposure, but researchers said they couldn’t prove the symptoms were caused by a nuclear test.