Note: Issued yesterday, the notice warns that water protectors must evacuate by December 5; designates "Free Speech Zone."

A round-dance had just started to form at the center of the Oceti Sakowin Camp as men in puffy Carhart overalls dug their electric drills into wide sheets of plywood. Beneath a sky where stars competed to shine against the persistent glow of high-beams used by police, workers at the camp moved fast to install a roof atop a modest structure.

It was the first time crews had toiled away into the evening hours building dwellings meant to sustain the onslaught of a North Dakota winter. That it was taking place only hours after an eviction notice had been issued by the U.S. Army Corps of Engineers seemed deliberate.

“If the Army Corps wants to come here and clear things out, so be it,” said Paul Sherlock, 55. The Cleveland, Ohio man arrived on election night. Since then, he said, he has donated nearly $30,000 in building materials to help winterize the camp.

Sherlock’s resistance to the Dakota Access pipeline is not unlike the reasoning of thousands of others determined to brace colder temperatures and intensified clashes with police.

“Social-justice-wise, environmentally-wise, we have to change our ways, and if we don’t change our ways, there’s going to be a lot of suffering,” he said.

That suffering could come sooner than expected. On Friday, Colonel John Henderson with the Army Corps’ Omaha District issued a letter to Standing Rock Sioux Tribal Chairman Dave Archambault II. It was an eviction notice with a timestamp for Monday, December 5.

“Pursuant to C.F.R. 327.12, I am closing the portion of Corps-managed federal property north of the Cannon Ball River to all public use and access,” Henderson wrote.

“I do not take this action lightly but have decided that it is required due to the concern for public safety.”

Since this summer, thousands of indigenous people and their allies opposed to the $3.8 billion, 1,172-mile-long Dakota Access pipeline have journeyed to the borderland of the Standing Rock Sioux Reservation, staking teepees and tents along the confluence of the Cannon Ball and Missouri Rivers. The property, managed by the Corps, is ancestral Treaty land of the Great Sioux Nation. Until Friday the Corps had permitted Standing Rock Sioux tribal members and their supporters to occupy the plot — an area that the federal agency has leased for private grazing or haying purposes in the past.

In Friday’s letter, Henderson alleged that campers had conducted illegal activity: burning fires, disposing of waste improperly, and building unauthorized structures such as the kind being constructed on Friday night.

It’s unclear what prompted the USACE Omaha District Commander to send the letter the day after Thanksgiving. In a November 1 memo sent by the colonel, requesting Morton County Sheriff’s assistance against protesters, Henderson later admitted that he wrote the letter at the request of Morton County officials.

The notice from the Army Corps comes less than a week after Morton County Sheriff’s deputies sprayed rubber bullets, mace and water on more than 400 people demonstrating at a bridge blockade not far from the camps. Temperatures were below freezing when protectors were repeatedly hosed down by police that Sunday night, November 20. There have also been reports that concussion grenades were fired at protectors. Dozens were hospitalized, including 21-year-old Sophia Wilansky, who may face the amputation of her arm, and Cheree Lynn Soloman, who is fundraising for eye surgery.

“If you were concerned about the safety of the fucking people you would have taken your ass out there and you would’ve cut their fucking hoses,” lamented Kash Jackson, an Army veteran from Michigan. His Facebook LIVE rant was broadcast shortly after the Corps announced its warning to water protectors that anyone choosing to stay on Corps land beyond December 5 would be doing so “at their own risk.”

“You stand firm, Standing Rock,” Jackson continued. “You stand firm right where you’re at. They want to push you off that land. It’s not their land to begin with.”

In less than 12 hours, Jackson’s video had been viewed almost a million times. Meantime a GoFundMe page to help bring veterans to stand with Standing Rock was experiencing an uptick in donations. In his post, Jackson made it clear: Veterans are coming.

“They may have to bring the Army to get rid of us,” said Toni Cervantes with nervous laughter. The 65-year-old from San Francisco was on the front lines of the massive police raid of the “1851 Treaty Camp” on October 27.

RELATED: Conflicting Accounts Emerge After Treaty Camp Police Action

Manning: Desecration, Mace and Police Snipers With Rifles at DAPL Front Lines

“There will be a worldwide uproar if this is done as violently by the militarized police as it has been,” Cervantes said. “I can’t even imagine. I’m just praying for a peaceful end to this whole thing.”

Water protectors are not the only ones looking forward to a safe and near end to the ongoing conflict. After another prayer demonstrations in Bismarck, this time at the Kirkwood Mall, the patience of area residents is wearing thin.

“Why do protesters have to come to the mall on the busiest day,” said Jami, referencing the post-Thanksgiving shopping tradition known as Black Friday. “It’s an invasion.”

Jami requested to withhold her last name. Nearby, two young girls clanged bells, a Salvation Army donation bucket between them.

“I don’t even feel safe just leaving my daughter and go walking through the mall,” she said. “And she’s ringing bells trying to get charity.”

With a dwindling tolerance for the Dakota Access dispute, there is also an impatience building for elected government leaders to resolve the issue once and for all. For water protectors, it means a repeated plea made to President Barack Obama.

“Knowing that [Obama] has held our babies at Cannon Ball, we know that he will do the right thing,” said Phyllis Young, former Standing Rock Sioux tribal councilwoman. Obama visited the reservation in 2014.

RELATED: President Obama Follows Visit With Strong Action Plan for Indian Country

Late Friday evening, Young sifted through stacks of documents — old case law files about water rights, even the Fort Laramie Treaty of 1851. Despite the Corps’ eviction notice, she hadn’t lost faith.

“We know that he will protect us and that he will help us,” Young said. “I have no doubt about that. Sometimes blessings come in disguises, and I pray for him everyday.”