CANNON BALL, N.D. (AP) — Dakota Access oil pipeline protesters in North Dakota have set up a new camp on private land recently purchased by the development company.

The opponents say the area rightfully belongs to Native Americans under an 1851 treaty, and they are vowing to stay put until the project is stopped.

Protests have been ongoing in the area for months, but the latest move marks the first time demonstrators have moved directly in the project’s path.

Morton County Sheriff’s Office spokeswoman Donnell Preskey says authorities “don’t have the manpower” currently to remove the more than 100 protesters.

Sheriff Kyle Kirchmeier says authorities put out a call for help earlier this month and several states are sending officers, though he would not say if the goal was to remove the protesters.