A satellite image of the Yongbyon Nuclear Scientific Research Center in North Korea. GeoEye via AFP

Commercial satellite images show that a key reactor at North Korea’s Yongbyon nuclear research facility may have resumed production of plutonium for nuclear weapons, according to an article posted on 38 North, a website dedicated to analysis of North Korea.

Analysts Frank Pabian, Joseph Bermudez and Jack Liu said the photos from February 25 indicate that the 5-megawatt reactor at the facility continued to show signs of operation as indicated by steam-vapor plumes emanating from the generator hall and river ice melt near the reactor.

The latest assessment follows spotty signs over the past year concerning the reactor’s operational status.

“If the reactor is operating again, as the evidence suggests, it means North Korea has resumed production of plutonium presumably for its nuclear weapons program,” the analysts said.

However, the experts couldn’t rule out the possibility that Pyongyang had taken earlier steps to disguise signs that the reactor was being used to process plutonium.

The satellite images also showed that a new military encampment has been built near the nuclear complex. “It is unclear what specific role this military camp will play, but it could be to support new construction and/or improve site security,” they wrote.