BISMARCK, N.D. (AP) — Protesters of the Dakota Access pipeline are increasingly divided over how to stop the project.

Older demonstrators argue for peaceful protest centered on prayer, but younger activists are pushing for more militant and aggressive tactics.

The differences came to a head last week after law enforcement officers in riot gear forced hundreds of protesters off an encampment on private property, prompting some demonstrators to torch three vehicles on a bridge.

Chief Arvol Looking Horse, a spiritual leader of the Great Sioux Nation, told The Associated Press on Monday that leaders of seven tribal nations are deciding whether they will meet with representatives from the pipeline’s operator, Texas-based Energy Transfer Partners.

Looking Horse said tribal leaders would want any meeting to be on neutral ground. He said a meeting Wednesday in Bismarck is being discussed.