Amnesty International on Friday dispatched human rights observers to the Standing Rock Sioux Reservation in North Dakota, a day after police with military equipment arrested over 140 people and used pepper spray, Tasers, sound cannons, bean bag rounds and rubber bullets against opponents of the proposed Dakota Access pipeline. Native American water protectors who were arrested on Thursday say police wrote numbers on their arms and housed them in what appeared to be dog kennels, without bedding or furniture.