North Korea has relied on dug in artillery pointed at Seoul to act as a deterrent since the end of active hostilities in the Korean War. The US would instantly see everything via satellite and both retaliate and eliminate the artillery. It would be too late for the 26 million residents of Seoul.
Nukes are more about threatening targets outside artillery range like Japan and US territories.
North Korea has relied on dug in artillery pointed at Seoul to act as a deterrent since the end of active hostilities in the Korean War. The US would instantly see everything via satellite and both retaliate and eliminate the artillery. It would be too late for the 26 million residents of Seoul.
Nukes are more about threatening targets outside artillery range like Japan and US territories.