That makes sense from a Western perspective where the primary value of nuclear weapons is deterrence. But for North Korea the calculus is different. North Korea

That makes sense from a Western perspective where the primary value of nuclear weapons is deterrence. But for North Korea the calculus is different. North Korea already has a conventional deterrent in the form of artillery that could be fired at Seoul and do enormous damage in a matter of seconds. Instead, their goal with nuclear weapons seems to be nuclear blackmail to obtain food and other economic aid to prop up their dysfunctional economy and support their totalitarian regime. For that purpose, liquid fueled rockets are fine because they don’t need to be fired at a moment’s notice. So it’s not hard to see how a space program could be used to further nuclear aims.