By Jamie Crawford
North Korea may have begun to stack the rocket for an upcoming missile launch, according to an academic group's analysis of a recent satellite image.
The blog 38 North, run by the School of Advanced International Studies at Johns Hopkins University, had access to an April 4 image from a commercial satellite firm that showed what is consistent with operations to erect a rocket in anticipation of launch.
The image revealed some sort of enclosure around the work platform of the mobile launch pad that had not been seen in previous satellite images.
The platform was also enclosed by a canvas, 38 North reported, possibly to protect it from the elements but also to ensure any activity inside was concealed.
Whether the early stages of a Taepodong-2 missile have made it to the launch pad is unclear because of the shrouded activity.
In addition, 38 North reports that most of the fuel tanks for the first stage of the rocket have been removed from the building, indicating the first stage of the fueling cycle has been completed.
A security checkpoint for vehicles to enter the pad from other locations at the launch facility appears to have been established, the blog said. The barricade was not present in earlier satellite images of the site and could indicate an elevated level of security.
Based on previous North Korean rocket launches in 2006 and 2009, the timing of the work in the latest images would be on schedule for the North's stated time frame for the launch, April 12-16, 38 North said in its analysis.
And a U.S. official said from what the U.S. government has observed, "Right now it seems the North Koreans are on schedule for their announced mid-April launch window."
CNN's Pam Benson contributed to this story.