Photos released by North Korean state media purporting to show the demolition of North Korea's nuclear test site earlier Thursday.
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The purported demolition was carried out in front of foreign journalists deep in the mountains in the northeast portion of North Korea, according to The Associated Press.
At today's Pentagon briefing, Lt. Gen. Kenneth McKenzie said the U.S. is assessing the pictures of what happened.
"We're looking at pictures of it right now," said McKenzie. "And we don't have a final assessment, they obviously did some visible destruction of the entrance to the tunnel. I don't have a better answer for you than that right now."
Journalists from around the world flew from Beijing to Wonsan, on the east coast of North Korea, Tuesday and were taken on a long journey to the nuclear site near the village of Punggye-ri.
North Korean state media previously reported the dismantlement process would involve "collapsing all of its tunnels with explosions, blocking its entrances and removing all observation facilities, research buildings and security posts" and that foreign media were invited to cover the event to show the process in a "transparent manner."
ABC News' Luis Martinez contributed to this report.