While China supports the existence of North Korea, it would be a stretch to say that they control it. The CCP leadership has been exasperated by many decisions

While China supports the existence of North Korea, it would be a stretch to say that they control it. The CCP leadership has been exasperated by many decisions taken by the North Korean leadership, but they simply believe overlooking North Korea's erratic actions is better than allowing it to pass into South Korea or the USA’s influence.