Native American tribes and environmentalists have formed an alliance rarely seen these days to oppose an oil pipeline planned to carry oil across the United States of America's Upper Midwest, crossing the crucial Missouri River twice and cutting through wetlands and protected wilderness areas.

"Our water is sacred," said 40-year old Dionne Addison of the Northern Arapaho tribe, who brought her two young children from Wyoming to North Dakota to support the area Sioux tribes trying to block the Dakota Access Pipeline.  "I want to make a difference, and I want them to know they can make a difference, too," she added, referring to her children.

The numbers have swollen to more than 4,000 protesters at the edge of the Standing Rock Sioux Reservation, where the tribe has so far managed to stop or critically slow the work of laying pipe.  "I've been getting notifications from tribes all over the country that have caravans in route, so it's continuing to grow," said Standing Rock Reservation spokesman Steven Sitting Bear.

But the cooperation between the protesters and state officials that was beginning to take hold last week is crumbling.  Some of the more aggressive protesters flashed laser pointers at law enforcement helicopters monitoring the protest from high above the Great Plains grasslands, temporarily disorienting the pilot.  Aiming a laser pointer at an aircraft is a federal violation. Reports have been forwarded to the North Dakota Highway Patrol and the Federal Bureau of Investigation.

But it also seemed to spark a punitive action by the state of North Dakota - the homeland security director ordered the removal of state-owned trailers and water tanks from the Dakota Access Pipeline protest campsite to protect them from damage.  "Based on the scenario down there, we don’t believe that equipment is secure," said Homeland Security Division Director Greg Wilz.

Only 29 protesters have been arrested for minor infractions such as disorderly conduct or trespassing.  The overwhelming majority of protesters are peaceful, but some have blocked traffic and there have been some threats made to police and to the excavating equipment.

"You have the pacifists and then you have the people who feel something should be done, and they're camped across the river from each other," said 32-year old Jesse Stevens who drove over from Wisconsin with two other members of the Menominee and Oneida tribes.  They put up their tent on the "peaceful" side.  "My point in coming out here was some kind of action, regardless of whether it's life-threatening or not," he said.  "This is our land, our people."

Meanwhile, farmers further down the route in the all-important agricultural state of Iowa are also trying to stop the pipeline.  A judge refused to back them on Monday, so they filed more appeals with state regulators.