Work on a 1,154-mile pipeline that would carry oil from North Dakota to Illinois was halted this week near the Missouri River, amid growing confrontations between members of the Standing Rock Sioux tribe and police guarding a construction site.

Native American groups and environmentalists have staged protests to block the Dakota Access pipeline for months from a “spirit camp” outside a pipeline construction site. The groups say the pipeline threatens sacred sites near the Standing Rock reservation and poses a risk to the tribe’s...