Amid growing speculation that North Korea may be preparing to conduct its seventh nuclear test, the latest satellite images showed lack of activity at the North's Punggye-ri nuclear testing facility, suggesting that preparations may be complete.

According to the U.S. Center for Strategic and International Studies' online outlet Beyond Parallel on Thursday, snapshots dated Monday showed no significant changes to the area outside Tunnel Number Three.

The authors of the online update interpreted the lack of development as the North possibly having finished all preparations for a nuclear test, as predicted by both South Korea and the U.S.

The ongoing construction activity on the road leading to Tunnel Number Four appears to have suspended, it said.

It remains unclear whether the regime is seeking to expand its testing capabilities to Tunnel Four, or if the activity is a part of a strategic deception.

The allies foresee that, should it conduct a test, North Korea will likely use the facility's Tunnel Number Three. Still, there is also speculation that Pyongyang may conduct the test elsewhere.