This episode was like someone said “Let’s do our version of The Undiscovered Country” and then gave it to a bunch of DS9 writers to execute. It starts with very Roddenberrian premise - the promise of a former enemy becoming an ally. But then it brings in the gritty realism of what war is really like, ala “The Siege of AR-558”, and the moral cost that war extracts - that maybe the monster you see is not just in the face of the enemy, but the face you see in the mirror, ala “Duet”, “In the Pale Moonlight” and the other morally grey episodes that often marked the best of DS9’s run.