In mid-November, the U.S.-Korea Institute at Johns Hopkins University said information from commercial satellite imagery suggests North Korea has tested at least two rocket motors as recently as September.
Separate reports from IHS Jane's Defense Week and the Bulletin of Atomic Scientists said North Korea may be engaged in activity related to its nuclear program.
The university group reported Friday that it reviewed commercial satellite imagery published recently showing the first two stages of a rocket were sent to a missile assembly building. This, it said, is "a clear indicator that the rocket stages are being checked out before moving to the pad for an eventual launch."
North Korean nuclear tests in 2006 and 2009 coincided with missile launches. The research group, however, said the timing of the latest activity raised questions as past launches have occurred in the spring or summer. Pyongyang, it added, typically provides specific information regarding launch plans.
"If Pyongyang follows past practice in preparing for a launch, it could be ready to fire a rocket as early as the end of the first week in December," the Johns Hopkins group stated.