This is a short story and/or novel that I read in the mid-to-late 1980s, most probably in a science fiction magazine that was published in the period of late 1960s to early 1980s. Based on a half-remembered (and possible incorrect) sense of the style, it is probably nearer the end of that period than the beginning.
The story's world is a post-apocalyptic situation, where remnants of civilization survive under the rule of various regional governments, many of which are dictatorships run by "strong man" warlords. I'm pretty sure that a limited nuclear war is the cause of civilization's collapse, but it may have been due to other factors. It may have been mentioned that larger and more varied types of governments still persisted in some parts of the world.
The story's location is a regional enclave run by a warlord, which I'm fairly sure was in North America, and which perhaps is in the less-populated parts of Canada (edit: actually Alaska). I think this enclave had regular conflict with other regional groups.
A traveller, which I want to say is from one of the larger polities to the south, comes to the enclave,
perhaps as part of a caravan as part of a blimp crew. He is relatively well-supplied with technology, some of which is offered for sale. Among these items is a functioning nuclear warhead (including, I think, a missile delivery system for it).
The warlord is very interested in purchasing this weapon, and the traveler's group agrees to sell it, but the catch is that it has an optical scanner that will require a particular code/pattern to launch. The warlord must surrender his son (or someone else close to him), who will have this code cauterized onto
his heart tissue the wall of an artery near his heart. (It may have been tattooed, instead, but I think it was burnt into the tissue.) The implantation of the code can be done safely using the technology available to the traveller, but to use the weapon later, the warlord will need to cut out his son's heart and present the code to the scanner.
This happens relatively early on, and the plot of the story is about subsequent conflict with the neighboring enclave(s) that causes the warlord to consider using the device. I don't recall whether he chooses to proceed or not.
EDIT: Having done some additional research on this myself, I came across the story "Iphigenia" by Nancy Collins, from 1991. It is definitely not this story (published too late), though it makes use of the same premise from Roger Fisher's article.