On Tuesday the Army Corps of Engineers gave notice to Congress that within 24 hours it would grant an easement allowing Energy Transfer Partners to move forward with construction on the Dakota Access Pipeline, which North Dakota’s Standing Rock Sioux tribe and thousands of allies have attempted to halt out of concern for water contamination, dangers to the climate, and damage to sites of religious significance to the tribe.

The federal government dismissed those concerns in its filing. “I have determined that there is no cause for completing any additional environmental analysis,” Douglas Lamont, the acting assistant secretary of the Army, wrote in a memorandum. “The COE has full responsibility to take the reasonable steps necessary to execute the requested easement.”

Two weeks earlier, after only four days in office, Trump signed two memoranda instructing federal officials to ram forward approvals for the Dakota Access and Keystone XL pipelines, both of which had been halted by the Obama administration after people mobilized across the U.S. to stop them. On Dakota Access, the Army Corps did just what the president demanded, waiving the standard 14-day waiting period before such a permit becomes official. The tribe has been left with just one day to rally a legal response.

Lawyers for the tribe say they will argue in court that an environmental impact statement, mandated by the Army Corps under Obama, was wrongfully terminated. They will likely request a restraining order while the legal battle ensues. Pipeline company lawyers have said that it would take at minimum 83 days for oil to flow from the date that an easement is granted.

Although the tribal government once supported the string of anti-pipeline camps that began popping up last spring, leaders have since insisted that pipeline opponents go home and stay away from the reservation. “Please respect our people and do not come to Standing Rock and instead exercise your First Amendment rights and take this fight to your respective state capitols, to your members of Congress, and to Washington, D.C.,” tribal chairman Dave Archambault said in a statement.

Still, the easement announcement is already activating pipeline opponents to return. A “couple thousand people” are headed back to the camps, including contingents of veterans, said former congressional candidate Chase Iron Eyes, a member of the tribe, in a video posted to Facebook.

Cedric Goodhouse, a Lakota elder who lives on the reservation and has been involved in fighting the pipeline since last spring, said it’s inevitable that the fight will spill outside the courtroom. “It’s going to come here to the drill pad. That puts us in a different spot,” he said. “It’s going to come to a head, and people are probably going to get hurt.”

“I’m pissed,” Joye Braun said, reacting to the Army Corps’ announcement as she drove back to Standing Rock. Braun had only returned home the night before to the Cheyenne River reservation in South Dakota to do some laundry when she heard the news. She threw her clothes back in a bag and got ready to return to the camp where she’s been living and resisting the pipeline. On her way out, she grabbed an extra item — her gas mask.

“People might think that it’s naïve, but I’m always hopeful that our laws will prevail. I know that Standing Rock Sioux tribe and Cheyenne River Sioux tribe and Yankton Sioux tribe will do everything that they can legally to stop this,” she said. But, she added, “I came here to support the grassroots people, and the grassroots people are telling me to stay.”

A message titled “This is the #NoDAPL Last Stand” posted by various native-led groups fighting the pipeline called for an “international day of emergency actions” on Wednesday. By Wednesday morning, a website described actions planned in 18 states.

“Water protectors remain on the ground at the Sacred Stone Camp, determined to stop the black snake, and we support them,” the statement added. “If you go, expect police violence, mass arrests, felony charges for just about anything, abuse while in custody, targeted persecution, and racial profiling while driving around the area, etc.”

The camps are in a state of transition, with the biggest, called Oceti Sakowin, in the process of being cleared in advance of spring floods. Two new camps have opened away from the flood plains. But the temperatures are subzero even for those who are at no risk of being flooded. “You really have to ask yourself, Can you withstand the temperature?” said Braun.

The police response is another factor. North Dakota Gov. Doug Burgum is calling for additional federal law enforcement support, even after the Trump administration agreed last week to send more Bureau of Indian Affairs agents.

Burgum’s government is supportive of the pipeline. The day after Trump’s executive pipeline actions, the governor launched a website called North Dakota Response, largely dedicated to publishing PR materials related to the pipeline fight. The site includes a “Myth vs. Fact” page, which includes a passage titled “Myth: Law enforcement fired water cannons on peaceful protestors,” declaring that a weapon used against protesters on November 20 was a fire hose rather than a cannon, despite myriad videos and photos from the incident depicting a crowd-control device indistinguishable from a water cannon, spraying water at demonstrators in below-freezing temperatures over a course of hours.

Posts on NDResponse’s Facebook page include various links to oil industry propaganda, including a site called “Pipelines101,” created by the American Petroleum Institute and the Association of Oil Pipe Lines, which declares, “Pipelines are energy lifelines, making almost every daily activity possible.” Another Facebook post encourages viewers to visit Energy Transfer Partners’ “Dakota Access Pipeline Facts” website.

Braun said the police presence on the ground seems to have intensified even as the population of the camps has diminished. A bright row of lights still illuminates the hills at night along the pipeline’s route above the camps, and low planes still circle the area routinely. But now a new outcropping of police has replaced a short-lived camp that was set up on private property, then cleared by police (via mass arrests) within a day last week. Security officials ride through the outskirts of the camps on snowmobiles.

Meanwhile, on Monday, the North Dakota House of Representatives approved four anti-protest bills, including one that would create a new misdemeanor for wearing a mask while committing a crime. Two others would increase penalties for trespassing and riot charges, which have been liberally bestowed upon Dakota Access protesters by police. A fourth would make it a felony to cause over $1,000 in economic harm while committing a misdemeanor. Still awaiting consideration is a bill that would shield from liability drivers who hit and kill demonstrators protesting on a road.