Intelligence officials claimed on Monday that satellite images show North Korea is digging an underground tunnel in apparent preparation for a third nuclear test.
The excavation at the Punggye-ri site where nuclear tests were conducted in 2006 and 2009 is in its final stages, according to a report by intelligence officials.
North Korea is preparing to launch a long-range rocket that Washington claims is a cover for testing missile technology that could be used to attack the US.