Photo: The Canadian Press

U.S. Army Corps of Engineers said Sunday that it won't grant an easement for the Dakota Access oil pipeline in southern North Dakota.

The decision is a victory for the several thousand camped near the construction site, who've said for months that the four-state, $3.8 billion project would threaten a water source and cultural sites.

The pipeline is largely complete except for the now-blocked segment underneath Lake Oahe, a Missouri River reservoir. According to a news release, Assistant Secretary for Civil Works Jo-Ellen Darcy said her decision was based on the need to "explore alternate routes" for the pipeline's crossing.

"Although we have had continuing discussion and exchanges of new information with the Standing Rock Sioux and Dakota Access, it's clear that there's more work to do," Darcy said. "The best way to complete that work responsibly and expeditiously is to explore alternate routes for the pipeline crossing."

The company constructing the pipeline, Dallas-based Energy Transfer Partners, had said it was unwilling to reroute the project. It and the Morton County Sheriff's Office, which has done much of the policing of the protests, didn't have immediate comment.

U.S. Secretary for the Interior Sally Jewell said in a statement that the Corps' "thoughtful approach ... ensures that there will be an in-depth evaluation of alternative routes for the pipeline and a closer look at potential impacts" and "underscores that tribal rights reserved in treaties and federal law, as well as Nation-to-Nation consultation with tribal leaders, are essential components of the analysis to be undertaken in the environmental impact statement going forward."

The federal government has ordered people to leave the main encampment, which is on Army Corps of Engineers' land, by Monday. But demonstrators say they're prepared to stay, and authorities say they won't forcibly remove them.

Earlier Sunday, an organizer with Veterans Stand for Standing Rock said tribal elders had asked the military veterans not to have confrontations with law enforcement officials, adding the group is there to help out those who've dug in against the project.

About 250 veterans gathered about a mile from the Oceti Sakowin, or Seven Council Fires, camp in southern North Dakota for a meeting with organizer Wes Clark Jr., the son of former Democratic presidential candidate Gen. Wesley Clark. The group had said about 2,000 veterans were coming, but it wasn't clear how many actually arrived.

"We have been asked by the elders not to do direct action," Wes Clark Jr. said. He then talked about North Dakota authorities' decision to move away from a key bridge north of the encampment by 4 p.m. Sunday if demonstrators agree to certain conditions, saying the National Guard and law enforcement have armoured vehicles and are armed.

"If we come forward, they will attack us," Clark said. Instead, he told the veterans, "If you see someone who needs help, help them out."