Riot police move in on N Dakota pipeline protesters
The scene was calm on Wednesday Image copyright AP
Riot police have begun removing protesters from private land in the path of the Dakota Access pipeline.
Dozens of officers in riot gear, some armed, moved in on Thursday assisted by trucks and military Humvees.
Two helicopters and a fixed-wing airplane flew overhead as officials made warnings over a loudspeaker.
Hundreds of police in riot gear and with heavy military equipment are preparing to remove Dakota Access Pipeline protesters from their encampment on private land in North Dakota.
The $3.7bn (£2.8bn) Dakota Access pipeline has prompted huge protests, notably in North Dakota where Native Americans have halted its construction.
It will run 1,168 miles through Iowa, Illinois, and North and South Dakotas.
As the police moved in, protesters parked cars on the main road near the camp and started a fire there.
The Morton County Sheriff's office said the operation began at 11:15am local time (18:15 GMT) and that protesters had refused to leave voluntarily on Wednesday.