North Korea appears to have tested a large rocket engine in recent days, in what could be a sign of preparations for the country’s first spy satellite launch in over a year.

NK Pro analysis of Planet Labs high-resolution satellite imagery shows new vegetation die-off between June 21 and 23 under the vertical engine test stand at the Sohae space launch complex.

New paving of roads and parking lots near the main launchpad appears in imagery from the same period as well, along with accelerated work on a pier that may be designed to receive ships carrying items or materials related to a launch.

Less pronounced vegetation die-off also appeared under the test stand between May 25 and June 1, possibly as a result of an earlier engine test. There has been increased vehicle activity throughout this month at an administrative building at the north of the complex and the hilltop observation stand DPRK leader Kim Jong Un has used to watch past engine tests. 

Kim was reportedly attending a secretive party plenum in the north-central part of the country from June 21 to 23, the period when the latest test appeared to occur, though it’s still possible he traveled to the Sohae complex on the northwest coast by helicopter or other means to oversee it.

The engine testing in recent days appears to be the first conducted at the Sohae vertical stand since exactly one year ago, which took place in the wake of a failed military reconnaissance satellite launch in late May 2024. Multiple tests also took place in the weeks before that launch.

However, since analysis largely relies on the detection of die-off under the test stand, it’s possible further tests took place over winter when there was little live vegetation to begin with. There may also be unidentified test stands in other locations.

The National Aerospace Technology Administration (NATA) successfully placed a military spy satellite into orbit in Nov. 2023. The following month, Kim demanded three more successful spy launches in 2024, but the DPRK eventually abandoned that plan after the launch failure last May. 

The delay in resuming launches appears related to development of a new engine, possibly with help from Russia, while Pyongyang has also initiated large-scale construction on a military factory known to produce liquid-fuel rocket engines in the past.

Elsewhere at the Sohae complex, construction has been ongoing in recent months on a tunnel connecting a rail line and rocket checkout building with the coastal launchpad, though this work still appears far from completion. 

The four previous launches from this pad involved transporting large Chollima-1 satellite launch vehicles (estimated to be around 29 meters long) by truck, and a launch in the near future would need to utilize this method again, as well as possibly a cargo ship and the new pier to bring in launch equipment.

Edited by Bryan Betts