The respondents here seem knowledgeable enough that I should take the opportunity to be more precise with my question: Why does North Korea need ICBMs when the

The respondents here seem knowledgeable enough that I should take the opportunity to be more precise with my question: Why does North Korea need ICBMs when they presumably already possess a regional nuclear deterrent, which itself should be adequate to secure their country against invasion? I guess the obvious answer would be that they want to be even more secure. But that is just a deduction on my part and as such, it feels like a bit of an unconfirmed piece in my understanding of the situation.