Factors that seem relevant to Korean peace:
- Pacifist RoK president
- Collapse of DPRK nuclear test site
- Chinese sanctions
- Maybe stuff Trump has done?
People talk about giving Trump a peace prize, but they also give contradictory lines of argument, saying that his threats were effective and credible as threats, but then also saying that they were so obviously jokes that they cheered up Kim and eased relations. Of course, Trump surrounded himself with Hawks, so maybe that increased credibility, but the U.S. didn't have military options, that aren't very limited in scope, so I doubt it.
People talk about the sanctions working, but up until just recently, other experts have said the people running industry in DPRK are adjusted to the sanctions and that the status quo might be preferred to disruption, so the only relevant difference in sanctions should be the Chinese sanctions.
Regardless, sanctions have been the policy of many administrations, so is it just luck/timing that things started working now? Is something critically different at the level of enforcement of the other sanctions too? Why is this change any different from what it would have been under any other president? What caused China to agree to new sanctions?