I’m sure the trace is out there but I could not find it in 5 or 6 minutes.
South Korea gave shipments of 300000 tons plus to NK in 2007 and looks like NK has been receiving tons of aid from other sources.
North Korea makes urea based fertilizer en masse, hence conversion to tons of urea nitrate is feasible.
Urea nitrate has 2X the detonation velocity of TNT so half the amount?
Someone with explosives background tell me if this is feasible.