I served with a US Army Mech[M113] Bn having two tours on the DMZ in '84-'85. We were running dismounted Squad recon & ambush patrols and manned two guard posts with one Plt each. Their tracks remained at Warrior Base. The US ARMY FOB along the DMZ. The rest of the Bn was running "training" missions along the DMZ and just South of it. There was a 155mm FA Plt right across the road from Warrior Base, called 4 PAPA 1.
When not on the DMZ our Mech Bn was with a forward deployed Inf Bde. About 12Ks South of the Z, along MSR 1.
There was also an Inf Bn there, at Cp. Liberty Bell. Right next to Pan Mun Jom, the site of the "Peace" talks that have been going on since '53.
We were always in Nork FA & missile ranges. We knew that might be the first notification of an attack. With their FA, raining HE, Incend. and Chem. rounds on our positions.
The USAF air assets, etc. would keep close watch on the border to see if they were moving units closer into attack positions. Sometimes we'd hear an SR-71 running photo, etc. missions along the border. It would sometimes make a sonic boom just to mess with the Norks.
And if war did break out our, the ROKs and hopefully the UN's mission was to push on to Pyong Yang, etc., and unify Korea under the South. If the PRC would get involved was the Wild Card.
Regardless the US, ROKs and hopefully the UN with overwhelming firepower, technical and tactical superiority would defeat the North. And not give up any ground. This time around. We were prepared now including the ROKs. Which then was spoiling for a fight and unify the Koreas. If they had to kill every Nork to do it.
We used to say our mission was as much to keep the Norks North and the ROKs South. The Norks were/are primarily an Infantry forces with heavy FA support and limited armor.
The only thing that kept/keeps the dynasty alive is the fact we can't take out enough of their FA and missiles before they'd hit Seoul. Causing massive losses to the city of 12 million today and 9 million in the '80s. But having get those shots the Norks would be seriously attrited by the US/ROK/UN(?) firepower. They'd get one shot to do as much damage as they could. Before they'd take heavy losses. With them eventually being defeated. And the regime being charged with crimes against humanity. Having about 40% of it population starving, running camps, etc.
And once again, would China risk a war with the US and it's Allies? That really wouldn't be good for business …