Concerning Kim Jong Un's white horse:
The white horse of Kim Jong Un references to King Dongmyeong aka JUMONG (58 - 19 BC) who succeeded in taking back a huge amount of (ancient Korean Gojoseon's) land back from the Han dynasty by reunifying the Korean people and founding the kingdom Goguryeo. Jumong is a national hero in both Koreas. His tomb is located near Pyongyang (NK) and the pic of Jumong on the white horse can be found in the temple next to his tomb.
Interesting article about Kim's white horse from 2019:
https://www.wilsoncenter.org/blog-post/parsing-the-propaganda-what-to-make-kim-jong-un-white-horse
Jumong:
https://en.wikipedia.org/wiki/Chumo_the_Holy_of_Goguryeo
Unification is a matter of time, though this anon personally thinks it will happen very soon.