is there any point in having nuclear weapons anymore?

[Mr Khan]

Ultimately you need a significant nuclear arsenal to pose a real military threat, and likely only America, Russia, and possibly China have that. Otherwise the threat is more psychological (you can do a fair bit of damage with one nuke, of course, but it wouldn't be enough for North Korea to just nuke, say, Seoul to stop South Korea, but in an ideal world, Seoul wouldn't get nuked at all, which really raises the costs of waging war on North Korea, playing to their advantage in negotiations.

This assumes, of course, that cooler heads prevail in the upper echelons of government. The kind of brinksmanship that led to World War I, for instance, could easily just see the nukes being used.