FILE - In this Oct. 5, 2016, file photo, heavy equipment is seen at a site where sections of the Dakota Access Pipeline were being buried near the town of St. Anthony in Morton County, N.D. The Army has notified Congress Tuesday, Feb. 7, 2017, that it will allow the 3.8 billion Dakota Access pipeline to cross under a Missouri River reservoir in North Dakota, completing the four-state project to move North Dakota oil to Illinois. The Army intends to allow the crossing under Lake Oahe as early as Wednesday, Feb. 8. The crossing is the final big chunk of work on the pipeline.  (Tom Stromme/The Bismarck Tribune via AP, File)
FILE - In this Oct. 5, 2016, file photo, heavy equipment is seen at a site where sections of the Dakota Access Pipeline were being buried near the town of St. Anthony in Morton County, N.D. The Army has notified Congress Tuesday, Feb. 7, 2017, that it will allow the 3.8 billion Dakota Access pipeline to cross under a Missouri River reservoir in North Dakota, completing the four-state project to move North Dakota oil to Illinois. The Army intends to allow the crossing under Lake Oahe as early as Wednesday, Feb. 8. The crossing is the final big chunk of work on the pipeline. (Tom Stromme/The Bismarck Tribune via AP, File) Credit: Tom Stromme

CANNON BALL, N.D. — With the federal government about to green-light the final phase of the Dakota Access pipeline, opponents of the project called Wednesday for protests around the world in an action they dubbed their “last stand.”

Some members of the Standing Rock Sioux tribe, which has been at the center of the debate for nearly a year, urged “emergency actions” via social media. The Indigenous Environmental Network told people to target fuel-transportation hubs and government buildings and to expect violence and mass arrests.

Protesters posted an online list of nearly 50 events in 23 states and the District of Columbia. In one early rally, several people were arrested for blocking public access to a federal building in San Francisco.

At a North Dakota encampment that’s been the focus of the pipeline battle for months, the mood was tense, with a few dozen people milling about on a frigid morning and refusing to talk about their plans. They ordered an Associated Press reporter to leave.

The Army said Tuesday that it would allow the pipeline to cross under a Missouri River reservoir in North Dakota. That crossing is the last big chunk of construction. The official permission to complete the pipeline, known as an “easement,” could come as early as Wednesday. The tribe maintains the move will violate its treaty rights, and its attorneys have vowed to keep fighting in court.

Although the pipeline attracted large protests long before Donald Trump became president, the call for more demonstrations was the latest example of the new administration taking action that could draw widespread dissent. Large protests followed Trump’s inauguration last month.

Chase Iron Eyes, an American Indian activist who has called on people to return to the main camp rather than leave, encouraged that again in comments in a statement and on social media.

“I’ll see you on the front line,” said Iron Eyes.