no, because they have a shit ton of artillery aimed at Seoul, tunnels under the dmz that can be packed with explosives, possibly nukes (which even if fizzlers could do a lot of damage)... and China.

there are in the perfect situation to do evil and get away with it.

Even funding a insurgency would be difficult. the population is so downtrodden they must have forgotten what freedom is (think 1984). the penalty for disobedience is your entire family in a concentration camp.