Sky News has witnessed a huge explosion during what North Korea claims to be the destruction of its nuclear test site in Punggye-ri.
Asia correspondent Tom Cheshire is the only British broadcaster invited to the demolition.
He said: “We hiked up into the mountains and watched the detonation from about 500 metres away.
“They counted it down – three, two, one.
“There was a huge explosion, you could feel it. Dust came at you, the heat came at you. It was extremely loud.
“It blew an observation tower to complete smithereens.”
Cheshire said he travelled 12 hours overnight in a train with blacked out windows before driving an hour through the mountains to arrive at Punggye-ri.
The group of about 20 foreign journalists invited on the visit were given a briefing by North Korea’s deputy director of nuclear weapons