Do we have world peace? I suppose that in comparison to a war involving large numbers of the world's nations, such as the Great War of 1914 to 1918 and World War II from 1939 to 1945, we might consider the current world situation to be relatively peaceful. But I doubt that that particularly signifies to the large numbers of civilians in many nations in today's world who find themselves constrained between violently opposed forces armed with military grade weapons supplied by companies of the developed nations, or those dominated by totalitarian governments.
While North Korea has demonstrated recently that they have both nuclear weapons and missile delivery systems, does this really make them a threat to other nations? While they might reasonably be considered a paranoid nation they certainly have significant reason to feel threatened by much larger nations with military forces far exceeding their own. The previous president of the United States of America labeled them a member of the "Axis of Evil", hardly conducive towards constructive conversation, although admittedly they would be unlikely to be receptive to any reasoned discourse anyway. But geographically they are a very small nation, their minute nuclear arsenal is exactly what the US claims theirs has always been, a deterrent!
Yes, they believe the world is against them, why shouldn't they, it is! They will almost certainly use their nuclear weapons if they are invaded from South Korea, but are we going to do that? I for one certainly hope not. As such they are not a threat to world peace or even peace in north-east Asia. The ruling elite in North Korea have it sweet in comparison to everyone else in their nation; while they will vigorously defend that, why on Earth would they throw it away if they are not threatened? They will periodically posture to satisfy their egos, but they will do nothing that might seriously threaten their own dominance within their own nation. More than fifty years of "war" without military conflict on the Korean peninsula should make that clear to anyone with an iota of sense.
Iran, as far as we know, does not yet have nuclear weapons. However, while North Korea is essentially an isolated nation, Iran is a Muslim nation with a dominating theocracy. They exist in a middle-eastern region surrounding by nations with large populations that follow similar religious beliefs. The concept of jihad or religious war is a foundation concept accepted by not only many within Iran but large numbers throughout the middle-east region. While they fought a bitter war with Iraq for several years not long ago, the current Iranian political and religious leaders consider the United States of America to be a nation of Christian Crusaders determined to crush them. The current demonstrations probably make them think that the change of US presidents simply represents a change in tactics rather than a change in attitude.
The persistent ongoing situation in the middle-east offers far more volatility to the world situation than any possible political situation regarding North Korea. The West's economic and industrial situation continues to rely heavily on petroleum products, a significant proportion of which are supplied by middle-eastern nations. Military conflict with Iran, even without any weapons of mass destruction, would have extreme impacts on the economies of the West. The instigation of a religious war between Islamic nations and those they perceive as Christian could be catastrophic, even though many in Western nations consider their countries as secular and themselves as agnostic or atheist.
Neither North Korea nor Iran is a threat to world peace on the basis of themselves. Neither nation treats their civilians in an acceptable manner, but they are certainly not alone in that behavior. Burma, China and several African nations are at least as bad. The leadership of both nations live far more luxurious lives than their citizens, but so does the leadership of the United States.
Can the United States justify decrying the possession of WMDs by other nations when the US almost certainly has the largest stockpiles of nuclear, chemical and biological weapons in the world? The US can hardly claim to be the most ethical of nations when it probably has the highest proportion of its citizens incarcerated in prisons within the Western world and comparatively abysmal animal welfare legislation.