Why is North Korea opposed to South Korea hosting the Nuclear Security Summit 2012?

Nuclear Security Summit is a conference to prevent nuclear terrorism. North Korea's nuclear issue is not in the agenda; therefore, there is no reason for North Korea to complain. Leaders from all over the world will gather and discuss international peace and safety in the Nuclear Security Summit. If North Korea provokes South Korea during the summit, it will be a great challenge against world peace and safety; therefore, we are making a full defensive preparation against any emergency.