That is how war happens. Leaders who for various reasons taunt and provoke each other, implementing what to either populace seems a reasonable policy. (NK would like to be able to defend against the US, so they get nukes. The US would like to not be nuked, so they agitate strongly against them). Alas, these policies are in conflict, so tensions rise.
At some point, a small event - a misunderstanding, a border skirmish, etc - happens. In the context of already ratcheted up tensions, it spirals out of control because everybody feels the need to react quickly, before the other side escalates.
Nobody says "over my dead body". Everybody takes the next step, a step that's entirely reasonable from their perspective, but opens up "reasonable" steps for the other side. The core problem is that neither side considers the needs of the other side.
Peace requires active communication to constantly de-escalate and compromise, from both sides. An interest in a common good. War is what happens when you lose that and move to self-interest.