I cant speak for the possible usage of Llamas and Alpacas in combat, though maybe one of my South American counter parts could weigh in on the liklihood of releasing the Camelids of War. But in North America the only animal that may have been used would have been the domesticated dog. Dogs were commonly found across North America, and probably would have served to help defend a community in someway. Dogs make for great sentries, they can warn you of newcomers and are usually pretty good at seeing, hearing, and smelling those trying to approach your dwelling. The nature of conflict in pre-Columbian North America centered around raiding which itself focuses on swift actions to catch an enemy unaware. Ambushes occured both within and outside the confines of your community, and with this in mind it is plausible that dogs as travel companions as well as living in town could have helped to combat the ability for an enemy to sneak up on you. However this is a pretty universal human usage of domesticated dogs, and would not have been as much of a focus for warfare as other domesticated animals.

One quick side note would be that dogs were sometimes used for transport beyond the stereotypical sled dogs of the north. But again I do not think this was used primarily for warfare and any benefit from it would have been a result of transport becoming easier in general as opposed to dogs being used primarily to transport items for war.

TLDR: the only animal that was domesticated and that would have played any role during conflict was the dog, however dogs and humans have such a deeply linked relationship that any benefit in warfare would have most likely been only an added benefit and far from the sole reason these communities had domesticated dogs.