republicans are pushing back. a briefing for the full house has been add. u.s. military observing significant activity at a north korean nuclear testing site. a new digging effort at a tunnel suggesting a nuclear test could be imfluorescent. paula hancock is tracking developments live from seoul. good morning, paula. >> reporter: hello. there's satellite imagery is the key for experts to find out what's happening. u.s. defense officials do see increased activity in digging at the entrance of one of the tunnels. but that might mean a sixth nuclear test is not imminent. suggesting there's more work to be done. we were heard they were primed and ready for that nuclear test.