Although the area is peaceful now, South Korea is located in a potentially volatile area. China and Japan both have powerful armies and North Korea claims to have nuclear weapons. If a conflict should arise, it is essential that South Korea, as a United States ally, be able to defend itself as well provide a platform and resources from which United States troops stationed in that area can provide immediate assistance.
South Korea should not be allowed to have nuclear weapons, but neither should the North. Nuclear weapons are suicidally insane, and should not be tolerated. There's no reason these weapons should exist, and for once in our lifetimes, our leaders can't just fool themselves out of this situation. Something needs to be done about this threat.