Doesn't matter how many people say "the enemy of my enemy is my ally" - it's still not true. Ignoring the bad behaviour of allies doesn't make it go away; it makes you culpable. By continuing to ignore the threat of the North Korean state not only to its neighbours and possibly the US, but to its own people.
I remember living in South Korea during the September 2011 attacks on the US; to my Korean friends, it seemed a tragic but distant "over there" problem. They lived in the shadow of a much more present threat. I had the chance to set foot in North Korea at Panmunjom and look North Korean soldiers in the eye - they are made of the same flesh and blood as are their Southern cousins. The gap between them is less a matter of walls, landmines and flags than it is one of culture, experience and fear, but both of these chasms can be bridged.
Someone just has to see the path and be willing to lead people forward. China could be that leader; their leadership could build some positivity into China's brand and increase their international respect quotient in the process. To do that, though, they need to stop looking at themselves as a future umbrella and instead see themselves as drops in the ocean.
There stands a train station in South Korea with a sign that says "To Pyeongyang;" everyone will be a little better off when that train can leave its station.
