Satellite picks up 'activities' at nuclear test site
INCREASED activity at North Korea's nuclear test site picked up by satellite could suggest that further underground atomic explosions could be in the pipeline.
North Korea last month threatened to conduct its fourth nuclear test and there's been speculation it may do so as President Barack Obama travels to Asia this week.
The US-Korea Institute at Johns Hopkins School of Advanced International Studies said recent images appeared to show movement of crates and possibly lumber near tunnel entrances at the northeastern mountain site of Punggye-ri.
It said that more movements of vehicles and equipment were detected in the weeks before previous detonations.
South Korea's Defence Ministry also said it had detected "various activities" at Punggye-ri, where North Korea has conducted three nuclear tests since 2006, the latest in February 2013.