4 ideas
A platoon of young Danish volunteers arrives in Helmand believing it is on a stabilization mission. The novel shows soldiers sent to impose order ending up conducting a private war with no front line, one that extends into Denmark itself.
Every act of retaliation in the novel is justified by an earlier wrong, so each party experiences itself as responding rather than initiating. Once violence is framed as reply, no one can locate or claim the first stone. That makes stopping look like capitulation, and the cycle sustains itself regardless of anyone's original aims.
The soldiers do not become brutal through a single decision. Each small transgression, such as a harsh search, a reflexive shot, or an unreported abuse, becomes the new baseline that makes the next one feel ordinary. The group's shared silence acts as the ratchet, because what no one objects to becomes what everyone does.
Look at Denmark's presence in Helmand as participation in someone else's war, joined for alliance standing rather than any clear national purpose. From that angle, the soldiers' disorientation is structural rather than personal. When the political goal is simply to be seen participating, the troops on the ground inherit all of the risk and none of the meaning, and that vacuum gets filled by loyalty to the unit and by vengeance.