Nucs: Destructive or Defensive?

In class the other day we touched on North Korea and its role in the world, as well as decisions that the country has made that are questionable. A hot topic concerning N. Korea is their nuclear weapons, and the their nuclear program has recently been restarted. The United Nations officers were also kicked out of the country and Kim Jong-il is asserting his power forcefully. The United States is working to get them to negotiate and compromise because they are a rising danger if more nuclear weapons are made that are more advanced. But the question that comes to my mind is this: why does there need to be nuclear weapons? Do countries spend so much time and money on creating them to defend their country or with the intention if attacking another? In North Korea, unknown numbers of people have starved to death while money flowed into the country's military program. Money is being spent on bombs and not on nourishing innocent people. What does having nucs say about a country? When one country decides not to cooperate with the rest, there is discomfort and unsureness. But why can't we all just get along? There are so many factors to be taken into consideration about North Korea and their relationship with the world, but what needs to be said to make them cooperate? When we talk about war, nuclear weapons are always something that come to mind. What I don't understand is how having nuclear weapons in your country is comforting. They're nuclear weapons. No one should have them. They are disastrous in every way. In class we posed the question "what does it take to provoke a war or conflict resulting in violence?" But really, is there anything that should provoke such violence? Because North Korea isn't cooperating, does that mean some sort of war is inevitable? I feel like I'm posing so many questions, but I really don't know the answers to them. Nuclear weapons should not exist period, even if they are only for means of defending. If no one had them, no one would need them to defend. But can we trust that other countries won't lie or be secretive with their nuclear program? So much of me wants to be optimistic and say that a nuclear weapon-free world can happen, but i don't know if that's possible.