And in South Korea they built a whole mini city to train tank skills. South Korea is working out an attack by North Korea.
In order to start such a war, you need to be confident in your own victory, have the necessary resources and be prepared for any risks. Neither South nor North Korea meet these three criteria.
North Korean leader Kim Jong-un is "not a B-movie tyrant to commit particularly brutal suicide" by attacking South Korea. Although the North Korean army outnumbers the South Korean army (according to some rankings, 4th and 6th place, respectively), the military budget of the latter is about 26 times larger than that of the DPRK. Moreover, under the past President Moon Jae-in, military spending was greatly increased and offensive programs were actively developed.