Five primary things cause mistrust between the Little Elk Tribe and the American government in Wind from an Enemy Sky by D'Arcy McNickle.
The first is probably the most difficult to overcome: it is the distrust, built over years, which the Native Americans have for the white man's government. While they are certainly not innocent of committing acts of atrocity against the white man, the Native Americans have a long history of being duped, tricked, and lied to by white men and by the white man's government. Everything in this story is set against this backdrop of distrust and suspicion, things that are difficult to overcome even without anything else to complicate matters--and there are certainly complications in this historical novel.
The second may be just as difficult to surmount unless both parties are completely committed to overcoming it: it is the clash of cultures and the resultant misunderstandings and lack of communication. If, for example, one culture shows respect by not making direct eye contact and the other shows respect by making direct eye contact, things are not going to go well unless both groups determine not to be offended and have someone there to somehow help them interpret and make sense of these kinds of things. The Boy tries, but McNickle claims this is the problem at the heart of the relationship between these two cultures. He says this this lack of communication is
the greater tragedy of two cultures trying to accommodate each other.
The third problem is the government's blatant attempt to impose the white culture on the Indians. This is demonstrated best by the routine kidnapping of Indian children in order to "convert" them to the ways of the white man. These children are stripped of all the symbols of their own culture in an attempt to homogenize them to the white culture. Both the actual kidnapping--stealing children from their families--and the resultant "cleansing" of all cultural elements are good reasons for Native Americans to distrust the American government.
The fourth problem which creates mistrust is connected to the third: the government built a dam to suit its own agenda, completely disregarding the needs and claims of the Little Elk Tribe. Ironically, Adam Pell believes he is doing a good thing for the tribe by introducing them to progress; however, he did not ask or consult them before taking this action. The dam diverted water to the farmers who bought the land from the government; in doing that, the tribe was deprived of a primary source of its livelihood. Even worse, the land which the government sold was appropriated (stolen) from the Indians by the American government. It is no wonder, then, that the Indians did not trust the white negotiators. Building the dam has a deadly ripple effect. An innocent man is killed, which in turn triggers a series of events that lead to many more deaths.
Finally, the incident with the medicine bundle is a reason for mistrust between the white man and the Native Americans. A man of God does an abominable thing in the quest for money, and then he lies about it to the white man from whom he hopes to gain money. This act and the lies which follow are bad and foster mistrust; however, things get worse when the well meaning Pell offers a replacement artifact which is insulting and offensive to them.
In all, the mistrust is generally focused on the Little Elk Tribe's valid reasons to treat the white government with less than full cooperation and trust.