But a pragmatic one. At this point with how tightly they continue to hold to the failing empire, with how they beckon to their calls for shells for Nazis in Ukraine or joining their groups for isolating China, they are a vassal state and the US is simply not going to allow them to re-unify peacefully.

Realistically what the US and the Korean puppets in the south want is an East Germany situation which is as Un points out is absorption and negation of the socialist state by the capitalist one. That's the only kind of re-unification or even growing closer together they would accept.

It was a valiant and worthy effort to attempt to compromise, to offer peace, to try diplomacy but the south does not have enough people aware of the propaganda to resist it and the leadership are of course all puppets and American loving liberals and the American interest in maintaining a fascist buffer against communism and a staging area that close to China is too great. The old in Korea like the old in Taiwan who might know better and have some experience with the depravity of the Americans and the earnest goodness of the communists are a dying minority.

Now with Russian ties growing stronger and the alliance of resistance against US hegemony which includes China, there are opportunities for the DPRK that do not involve compromise with lying, backstabbing, fascists.

The US has made itself a great candidate for becoming a vassal state, since there is very little material wealth generated domestically. Imagine if/when American businesses in China/Russia (I can't imagine there are any in NK right?) are nationalized. Especially if China stops exporting to the US. That would devastate the American economy, shortages of everything everywhere, and no productive capacity or expertise to fix it.

Capitalism is abandoning the empire.

NK advances past what SK is able to respond to

they've had that for a long time, it's that the US & Japan are supposed to back SK up and make up the difference

You mean that time the USA told Japan to not vacate the peninsula until the USA military arrived, took over the imperial colony of Japan on the peninsula, created an artificial border in the middle of a sovereign nation, and then used a crossing of that fake border to justify bombing nearly every single structure in the North until the military had to acknowledge there were no more targets left to hit, so instead they amped up their napalm campaign and Koreans needed to live in caves to survive while the USA occupation of South Korea was a racial and sexual domination playground until eventually they found enough compradors in South Korea to build a government with an air of legitimacy to provide cover for essentially turning the entire Southern portion of the peninsula into a USA military base and industrial base? That Korean War? The one that killed millions of civilians?

Technically the first never ended. Korean War 1.5 maybe?

The US is still at war with the DPRK. We've been in an armistice, a stalemate, for 70 years.

To be honest slamming the door on SK with all the sanctions on their country and the material suffering risk would have been irresponsible. I think this is mainly in response to not just the decades of failed peace processes and the recent provocations but also the new global economic reality that with Russia now isolated from the west and in their corner and China as well, shutting that door doesn't mean the same potential death sentence it might have meant in say 2004 or 2014.