I learned about it from mostly western sources and Wikipedia, so you know it must have been bad when their war crimes can’t be glossed over by their own propaganda outlets. They bombed the entire peninsula indiscriminately, killing literally millions of civilians.

More Bombs were dropped on the Northern Korean peninsula than the entirety of bombs dropped in Europe during WW2. Including chemical ordnance like Napalm.

I recommend look up the Sinchon and No Gun Ri massacres, and at the merciless bombing campaign they led against the DPRK.