A man takes part in a march with veterans to Backwater Bridge just outside of the Oceti Sakowin Camp during a snow fall as "water protectors" continue to demonstrate against plans to pass the Dakota Access pipeline adjacent to the Standing Rock Indian Reservation, near Cannon Ball, North Dakota, December 5, 2016.

Activists are threatening "mass resistance" to President Donald Trump and the Army Corps of Engineers on the hotly disputed Dakota Access pipeline — and it could be difficult for the White House to counter the movement.

Acting on an order from Trump, the Army Corps of Engineers on Tuesday said it would grant the easement that Energy Transfer Partners needs to finish the final stretch of the pipeline. It also canceled an environmental review the Corps said it would undertake while President Barack Obama was still in office.