The South's current government is ridiculously conservative. Rolling back labour laws and women's rights were pillars of their election run. They'll do whatever the US tells them to. It shouldn't come as a surprise that peaceful diplomacy is not at the forefront of their mind.

It's honestly pretty cyclical, they bounce back and forth between more diplomatic minded leadership and more warhungry. They are much more in the antagonistic phase of their cycle right now.

Unfortunately the current situation appeases the global powers the most. China and Russia will not stand to have a US allied united Korea so close to Beijing and Vladivostok, which means a united Korea is a neutral, non US aligned Korea, which the US does not want. Having North Korea be a buffer state between China/Russia and the US aligned South Korea is the most stable option, and as a result North Korea knows that it can do whatever it wants and still be propped up by Beijing, just as it has since the Korean war

An archived version of the article

There’s no point in negotiating with a dictator whose primary goal is to remain in power. A peaceful end to the conflict means the death of Kim at the hands of the oppressed.

This is like asking a kidnapper to kindly release the hostages or we will ask again later.