The U.S. Army Corps of Engineers says it has "no plans for forcible removal" of protesters who have been camping in North Dakota to protest the Dakota Access oil pipeline.
The Corps says in a statement Sunday that it "is seeking a peaceful and orderly transition to a safer location."
The Corps notified tribal leaders Friday that all federal lands north of the Cannonball River will be closed to public access Dec. 5 for "safety concerns." The agency says those who choose to stay do so at their own risk. The Corps says anyone on the property north of the Cannonball River after that date will be trespassing and subject to prosecution.
The land to be closed includes the main protest camp, about 50 miles south of Bismarck.
Tactics used by the Morton County Sheriff's Department have drawn criticism from the Standing Rock Sioux's tribal leader, protest organizers and celebrities.
Standing Rock Sioux Chairman Dave Archambault said he and Kirchmeier have met many times and each meeting has been tense and unproductive. "I don't think aggressive force is necessary and he thinks it's necessary," Archambault said.
In the most recent clash between police and protesters, which was near the path of the pipeline and happened last week, officers used tear gas, rubber bullets and large water hoses in freezing weather. Organizers said at least 17 protesters were taken to the hospital, some for hypothermia and one for a serious arm injury, and one officer was injured.
Archambault called the confrontation an act of terror against unarmed protesters that was sanctioned by Kirchmeier.
"His job is to protect and serve, not to inflict harm and hurt," Archambault said.
But Kirchmeier, who has the backing of the state's Republican governor and attorney general, defended officers' actions. He and other authorities said officers were assaulted with rocks, bottles and burning logs.
"Social media has been very bad and it has turned out like law enforcement is building the pipeline," he said. "I can't stop the pipeline. My job is to enforce the law."
President Barack Obama raised the possibility of rerouting the pipeline earlier this month, and construction on the last remaining large chunk, which is on federal land near the reservation, was halted by the Corps for the time being. But Kelcy Warren, CEO of pipeline developer Energy Transfer Partners, told The Associated Press the company won't do any rerouting.