A U.S. website that monitors North Korea says satellite imagery shows a high level of activity at the isolated nation's nuclear test site.

A man watches a television news broadcast at a railway station in Seoul on July 9, 2016 (Photo credit should read JUNG YEON-JE/AFP/Getty Images)

The website 38 North said Monday the commercial imagery taken July 7 appears to show supplies or equipment near a tunnel entrance at Punggye-ri (PUNG-gare-ree), where North Korea has conducted four underground nuclear test explosions since 2006. There is also a vehicle at a nearby support building and what may be mine ore carts.

The website says it is unclear whether this activity is for maintenance, excavation or preparation for a fifth nuclear test. It concludes that North Korea is ensuring that the facility is in a state of readiness.

The last test explosion took place in January and drew the toughest international sanctions yet.

(Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)


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