Nuclear arms have political utility. For countries with formidable nuclear arsenals and the means of delivering warheads, nuclear weapons can be used to extort political concessions from non-nuclear-armed states through terror and intimidation. No country exploits the political utility of nuclear weapons as vigorously as the United States does. In pursuing its foreign policy goals, Washington threatened other countries with nuclear attack on 25 separate occasions between 1970 and 2010, and 14 occasions between 1990 and 2010. On six of these occasions, the United States threatened the DPRK.  There have been more US threats against North Korea since. (The United States’ record of issuing threats of nuclear attack against other countries over this period is: Iraq, 7; China, 4; the USSR, 4; Libya, 2; Iran, 1; Syria, 1. Significantly, all these countries, like the DPRK, were under communist or economically nationalist governance when the threats were made.)
Nuclear weapons also have political utility for countries menaced by nuclear and other military threats. They raise the stakes for countries seeking to use their militaries for conquest, and therefore reduce the chances of military intervention. There is little doubt that the US military intervention in Iraq and NATO intervention in Libya would not have been carried out had the targets not disarmed and cleared the way for outside forces to intervene with impunity.
A North Korean nuclear arsenal does not increase the chances of war—it reduces the likelihood that the United States and its South Korean marionette will attempt to bring down the communist government in Pyongyang by force. This is to be welcomed by anyone who opposes imperialist military interventions; supports the right of a people to organize its affairs free from foreign domination; and has an interest in the survival of one of the few top-to-bottom, actually-existing, alternatives to the global capitalist system of oppression, exploitation, and foreign domination.