More than 2,000 U.S. military veterans are expected to join a protest at a camp in North Dakota on Friday where thousands of activists, braving frigid conditions, are demonstrating against a pipeline project near a Native American reservation.

Veterans Stand for Standing Rock will spend the day building a barracks at the Oceti Sakowin camp near Cannon Ball and coordinating with protesters who have spent months rallying against plans to route the Dakota Access Pipeline beneath a lake near the Standing Rock Sioux reservation, organizers said.

The veterans intend to form a human wall in front of police to protect protesters, who say the $3.8-billion pipeline poses a threat to water resources and sacred Native American sites.

State officials on Monday ordered activists to vacate the camp, on U.S. Army Corps of Engineers land, citing harsh weather conditions. Officials said on Wednesday they would not actively enforce the order.

"There is an element there of people protesting who are frightening," North Dakota Attorney General Wayne Stenehjem said on Thursday. "It's time for them to go home."

U.S. President-elect Donald Trump on Thursday said he supports the completion of the pipeline. Trump's transition team also said he supported peaceful protests.

Members of the North Dakota Veterans Coordinating Council denounced the involvement of veterans in a protest that has damaged property and asked them not to take part.

North Dakota Governor Jack Dalrymple has said it was "probably not feasible" to reroute the pipeline, but he would try to rebuild a relationship with Standing Rock Sioux leaders.

State officials never contemplated forcibly removing protesters and his evacuation order was mainly due to concerns about inclement weather endangering people, Dalrymple said. Frigid weather makes some aspects of pipeline construction more difficult, engineers interviewed by Reuters said.

The temperature in Cannon Ball is expected to fall to 4 degrees Fahrenheit (-16 Celsius) by the middle of next week, according to Weather.com forecasts.

The 1,172-mile (1,885-km) pipeline project, owned by Texas-based Energy Transfer Partners LP <ETP.N>, is mostly complete, except for a segment planned to run under Lake Oahe, a reservoir formed by a dam on the Missouri River.

Protesters, who refer to themselves as "water protectors," have been gearing up for the winter while they await the Army Corps decision on whether to allow Energy Transfer Partners to tunnel under the river. That decision has been delayed twice by the Army Corps.

(Additional reporting by Ernest Scheyder; Editing by Janet Lawrence)