The U.S. Army Corps of Engineers will not be granting the company building the Dakota Access Pipeline (DAPL) the easement it needs to cross the Missouri River, despite the project being nearly complete.

American Indians and environmentalists camped out at the project’s construction site hailed the decision a victory, while Energy Transfer Partners and pipeline supporters are bashing the Corps for reversing its stance on the project.

Army Assistant Secretary for Civil Works Jo-Ellen Darcy said the Corps would not approve the easement based on the need to “explore alternate routes” for the pipeline. It’s a stunning reversal from July 2016, when the Corps approved the easement for the project.

“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 in a statement.

“The best way to complete that work responsibly and expeditiously is to explore alternate routes for the pipeline crossing,” she said.

Her decision was criticized by DAPL supporters.

“This purely political decision flies in the face of common sense and the rule of law,” Craig Stevens, spokesperson for the Midwest Alliance for Infrastructure Now Coalition, said in a statement.

“Unfortunately, it’s not surprising that the President would, again, use executive fiat in an attempt to enhance his legacy among the extreme Left,” he said. “That the President continues to believe that he is above the law is simply un-American and it is this arrogance that working class Americans soundly rejected on November 8.”

The $3.8 billion, 1,172-mile pipeline made national news earlier this year when hundreds of American Indians and environmentalists converged on the project’s construction site near the Standing Rock Sioux reservation in North Dakota.

DAPL does not cross tribal land, but crosses under Lake Oahe, which Standing Rock Sioux officials claim contains sacred sites. The tribe also claims the pipeline could harm their drinking water. Lake Oahe is a man-made lake made in the 1960s when the federal government dammed up the Missouri River.

Activists claim the pipeline’s crossing under Lake Oahe is upstream from tribal drinking water intakes.

Protesters have been involved in tense stand-offs with security and police over the last few months, culminating in protesters being hosed and pepper-sprayed trying to block DAPL’s route. Pipeline construction equipment were also vandalized over the summer.

President Obama weighed in on the pipeline in September, telling protesters they were “making your voices heard.” Obama also said the Corps was looking at alternate routes for the pipeline to appease the tribe.

The Corps delayed its decision of whether or not to issue the easement across government land DAPL builders needed to complete the pipeline. Now, Energy Transfer Partners needs to figure out another way across the river.

“We wholeheartedly support the decision of the administration and commend with the utmost gratitude the courage it took on the part of President Obama, the Army Corps, the Department of Justice and the Department of the Interior to take steps to correct the course of history and to do the right thing,” Standing Rock Sioux Tribal Chairman Dave Archambault II said in a statement.

The Standing Rock Sioux sued the Corps in July to halt the project. A judge sided against the tribe, but the Obama administration quickly weighed in to delay the issuing of the easement.

“There is no reasonable logical, factual, environmental, or scientific reason for this not to be issued — in fact the Army Corps of Engineers had already recommended the approval of the easement,” Stevens said.

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