A United States Web site devoted to analysis of North Korea says new tunneling work has been spotted at the North's Punggyeri nuclear test site. 

The Web site 38 North, a program of the U.S.-Korea Institute at John’s Hopkins University, said Tuesday that recent satellite imagery of the Punggyeri nuclear test site has revealed new tunneling work being done in the West Portal area.  

The Web site said such tunneling work appears to have begun in late April and gathered momentum over the next few months. The Web site said "imagery from June first shows a large new spoil and tailings dumpsite along the road between the West Portal and the old dump site that went into a canyon to the east."

The Web site also said such tunneling work could be the construction of another tunnel at the West Portal or the repair of a tunnel at the West Portal area or could mean the clearing of debris from existing tunnels.  
 
38 North said these activities do not appear to be part of preparations for a nuclear test in the short-term and rather appear be long-term projects that may be necessary to conduct future nuclear tests.