North Korea appears to have started repairing a closed nuclear testing site, according to satellite images.
The Punggye-ri site was shut in 2018 and some parts were blown up, after leader Kim Jong-un promised to halt all nuclear tests.
The new finding by US analysts comes amid predictions the country could resume testing nuclear weapons and long-range missiles.
But analysts also say it could be years before Punggye-ri is ready for tests.
The satellite images showed “very early signs of activity” which took place only in the last few days, including construction of a new building, repair of an existing one, and lumber and sawdust at Punggye-Ri, according to a report by analysts from the James Martin Center for Nonproliferation Studies (CNS).
The pictures were taken on Friday by satellite imaging company Maxar.
The work indicates that North Korea “has made some decision about the status of the test site”, the analysts said.
One possibility could be a plan to bring the test site back to a state of readiness to resume nuclear explosive testing.
The move would align with an earlier statement issued by North Korea in January to “examine the issue of restarting all temporarily-suspended activities,” they said.
But the analysts called the new activity spotted at Punggye-ri “preliminary”, pointing out it could take “months, if not years, from being ready for North Korea to conduct nuclear explosions”. They added that this would depend on the extent of the damage inflicted to the site’s tunnels when it was closed down.
Another possibility, they said, was that North Korea may resume nuclear testing at another location.
Punggye-ri, located in the north-east of the country, was declared shut and allegedly dismantled in 2018, in what was seen as part of a diplomatic rapprochement with South Korea and the US.
International media were invited to witness a series of explosions which Pyongyang claimed would block tunnels and entrances, but officials refused to allow international inspectors to enter. Some worried at the time that the damage caused could be easily reversible.
Punggye-ri is believed to be North Korea’s main nuclear facility, and up until 2018 was the only active nuclear testing site in the world. North Korea has conducted six known nuclear tests since 2006 at the facility.
In August, the International Atomic Energy Agency said the North was appearing to re-start its Yongbyon nuclear reactor, raising concerns that plutonium for nuclear weapons was being produced at the reactor’s complex.
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