North Korea may be attempting to restart its Nyongbyon reactor, the nuclear facility used for making nuclear bomb fuel.  It comes amid increasing US-led international economic sanctions against the Kim regime and a United Nations push to put the hermit kingdom’s awful human rights record on trial at the International Criminal Court.

The U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies reports on its 38 North blog that recent satellite imagery shows activity at the site. Nyongbyon has a five-megawatt reactor that intelligence officials believe was used to produce nuclear fuel for past nuclear weapons test explosions.  The pictures show hot water draining from a pipe that collected steam off of the reactor, as well as snow melt on the roofs indicating activity inside.  There was also activity at the Yongbyon facility, which is thought to be used for enriching uranium.

Nyongybon had been shut down for five months prior to the new activity detected over the period from the end of December to about mid-January.  It can likely produce about 13 pounds of plutonium per year, about enough for one bomb.  It’s not known if North Korea has perfected making a weapons small enough to be mounted on the tip of a missile, but each test brings it closer.

Pyongyang has already conducted three nuclear tests, and recently threatened a fourth in response to the tensions with the US and Seoul. 

Earlier this month, North Korea offered to suspend nuclear tests in exchange for a temporary freeze on US-South Korea joint military exercises.  Washington said the offer sounded more like a threat, and rejected the offer.