- Cheonan Incident
- Yeonpyeong Shelling
- Baengnyeong Island
- Landmine deaths / rockets to south DMZ zones
I guess 'relative peace' to you means only a couple hundred murders in the past ~7 years.
And I'm not getting into things like Kaesong, Kim Jong-Nam, nuclear tests, ICBMs falling into the Sea of Japan, etc.
Glossing.