Area countries respond to North Korean belligerence
South Korea has developed weapons to deal with North Korean tunnels and cave complexes. Their precision missiles bore into the ground and explode underneath it. They would likely first target the artillery emplacements in caves across the border from Seoul. The South's army is well trained and unlike the North's is well fed. The Japanese have been building up their missile defense capability and modernizing their navy. I suspect that they and the US would target North Korean harbors and any craft that might leave them.