Alright, so I'm going to preface my post pretty heavily. First off, I was trained as a baby historian. I have my BA. I took it very seriously - my topics of study were often directed toward nuclear issues and the history of fascism/far-right ideologies. The courses I took, of course, covered a very broad range of issues and I am in no way specialized or academically trained in issues regarding Korean history and my grasp of the methods of military history is somewhat limited, though I did study under a pretty decent military historian who studied Ireland's independence struggle and Irish violence in North America, etc. I have never visited any part of Korea, I have not recently accessed academic articles on the topic, but I do try to stay up to date by reading books (Bruce Cummings, BR Meyers are good authors on the topic that much of the below will draw upon), certain websites (I follow Andrei Lankov on NKDaily, I also follow 38North and a few other publication), and listening to any podcast on the topic. I engage with the writings of talking head neocons like Gordan Chang and do my best to follow the issue as closely as I can without losing my mind.
Kidding about dicks aside, North Korea and the United States are in a very sensitive situation with so many mind bogglingly complicated factors at play. There are the interests of major global economic powers at stake (PRC, ROC, ROK, Japan, Russia, etc.) and there is a very long history that must be taken into consideration. I would like to clarify that for the sake of brevity I will use abbreviations for a lot of countries, ie Democratic People's Republic of Korea = North; Republic of Korea = South; People's Republic of China = Mainland; Republic of China = Taiwan, etc.).
The primary issue at hand is not actually nuclear weapons, though they greatly frustrate the calculus. The whole issue of the Korean peninsula is the matter of reunification. Just like Germany. The issue here, though, has always been reunification on whom's terms. The secondary, and most pressing problem, is nuclear weapons. From these two facets of the conflict flow my entire analysis and thesis.
It stands to reason that the entire pretext of nuclear weapons is regime preservation in the main, and having an added effect of leverage over regional neighbours (particularly should DPRK choose to militarily and forcefully reunify the peninsula). The current talk of a "bloody nose attack", something without international legal precedent since gunboat diplomacy in the Scramble for Africa, is terrifying and any US attempt to control the situation by force of arms will fail in its aims and lead to global conflict. The nature of Kim regime's legitimacy (reunification on our terms, racial purity, resistance against foreign forces) and its relationship with its weapons mean that in my view the weapons would not be fired in anger or a military strike as it would fatally undermine the regime. The use of the weapons militarily would be almost immediate should the DPRK be attacked by the US if the use of force was deemed existentially threatening to the Kim leadership and core elite. The DPRK could handle a limited ROK strike without losing legitimacy though it would greatly increase tensions. An attack by the US would mean that the DPRK leadership would be in a use it or lose it position. Without the immediate the deployment and battlefield use of nuclear weapons the weapons will be lost. A few could be squirreled away in an semi-operational state for later use in an insurgency, but the bulk of the weapons would be operationalized and used. Any US 'bloody nose strike' will lead to 1. massively increased tensions and suspicion/anger on the part of China, 2. massive retaliation on the part of the DPRK on the northern suburbs of Seoul with the option to further escalate the strikes, 3. Global economic uncertainty which would gradually strengthen the north's hand.
Now the big issue is reunification. I firmly believe that the driving issue is always reunification. No matter how cynical the actions at the time the military planning of the North is first to survive any outside threat and then reunify the Korean peninsula. This is ultimately fantasy on the part of the North in the 21st century. Up to the 70s it could have happened by conventional force of arms, but now, not so much. It would take decades of outstanding luck on the part of the north followed by decades of misery in the south to change the metrics of this. Reunification will likely be driven by the South against the wishes of China. In a moderate scenario you would have a confederal state of DPRK/ROK, which would gradually have the wealthy south absorbing the north more like Germany than...whatever now would be. Totally unprecedented in modern terms.
This of course is borne out in the phases of DPRK ideology in the post-Marxist environment. Since the 70s the DPRK has really not been a Communist state in ideological terms. In practical terms its command economy and symbology make it a passable semblance, but its total lack of internationalist outlook and deeply ethnocentric self-image, mean that it has long since ceased to be that sort of state. The main ideals are Juche, songun, and whatever Kim Jong Un is cooking up through increased prestige of the Workers Party of Korea. Juche, formulated by Kim Il Song, is often translated as 'self-reliance' and can be seen in terms similar to the autarky of Nazi Germany. The backbone of the state, has postulated by BR Meyers, is more from Imperial Japan than its Communist patrons. To this end, if you look at the relations of the Second World, DPRK was always looked at oddly, Kim Il Song often given advice that was not followed by Mao, Stalin, Khruschev, Brezhnev, and others. The collapse of its patron state in the 90s and the loss of industrial inputs for agriculture lead to the self-reliance ideology being supplanted by Songun, or military first, during the Arduous March (famine) of the 90s under Kim Jong Il. Military first made a lot of sense, the military was highly controlled and could be counted on for loyalty while the population starved. This was a process borne out across the whole of the Earth with states in Africa, Latin America, and Asia losing the patronage and economic support of the USSR. DPRK was hit particularly hard because of the advanced stage of mechanization of its agriculture. Once you take away the inputs of diesel fuel, hydro-carbon derived fertilizers, you eat into your grain reserves. Once those are gone price instability sets in. All the socialist world was more or less deeply in debt, barring outliers like Romania, but DPRK was just hit uniquely. So, when people talk about the failure of the state, it was kind of foretold that once the state became isolated it would fall apart agriculturally. Nothing unique about it, in fact. The scale of it, combined with once-in-a-century flooding, collapsed the state.
I'll revisit this but I've spent enough time ranting. I was super happy to find this thread and would be super interested in engaging and helping anyone learn more about this very interesting and tres relevant topic by suggesting readings, podcasts, and stuff to follow