FILE PHOTO: A sign stands in the entrance of the main opposition camp against the Dakota Access oil pipeline near Cannon Ball, North Dakota, U.S., February 22, 2017. REUTERS/Terray Sylvester
FILE PHOTO: A sign stands in the entrance of the main opposition camp against the Dakota Access oil pipeline near Cannon Ball, North Dakota, U.S., February 22, 2017. REUTERS/Terray Sylvester