Commercial satellite imagery on Dec. 23 of the Sohae satellite launching station, also known as the Dongchang-ri site, showed efforts to clear snow off roads, including the one leading from the vertical engine test stand to the VIP observation facility, 38 North said on its website.

The test stand itself remained snow-covered, it said. Entrance ways, parking lots and courtyards were also cleared, with snow-clearing patterns suggesting that nearby buildings were being staffed.

"Recent commercial satellite imagery of the Sohae Satellite Launching Station indicates that, while the facility is being maintained, there are no observable signs of preparations for either a rocket launch or engine test," 38 North said, adding that imagery from Jan. 14 also showed little other activity.

North Korea conducted what it called "important" tests at the facility on Dec. 7 and 13. The announcements spurred speculation that the regime was preparing to launch a long-range rocket in protest of stalled denuclearization negotiations with the United States.