Satellite images from last week show a high level of activity at North Korea's nuclear test site but it is unclear whether this was for maintenance or preparation for a fifth nuclear test, a U.S.-based North Korea monitoring project said on Monday, according to Reuters. A report on the 38 North website said the commercial satellite imagery from July 7 was not of sufficiently high resolution to determine the exact nature of the activity at the Punggye-ri test site, but it added: "It is clear that North Korea is ensuring that the facility is in a state of readiness that would allow the conduct of future nuclear tests, should the order come from Pyongyang."