I have read that NK has mostly outdated artillery pieces, 25 MiGs and older issue AK's, T-34/54/55/62 tanks the newest of them dating back to the '60s. The soviets supposedly sold them an entire WWII-ear artillery production factory that is actually still in operation today! Not much upgrading since the '80s. A modernized SK military could probably defeat them without our assistance.
SK probably wouldn't have much trouble defeating NK's outdated armed forces. The problem is the massive civilian casualties and economic destruction that would be caused by an NK artillery attack on Seoul. In just a couple of days, NK artillery could inflict enormous damage on SK. This is KJL's ace in the hole that keeps him in power. But you never know, some day we may invent a way to shut down his artillery in 10-15 minutes and then he'll have to do what we tell him or be gone.