In a setback for the Trump administration’s drive to ramp up fossil fuel development, and a tentative victory for the Standing Rock Sioux tribe, a federal judge on Wednesday ordered an expanded environmental review of the Dakota Access pipeline.

U.S. District Judge James Boasberg wrote that the U.S. Army Corps of Engineers “did not adequately consider the impacts of an oil spill on fishing rights, hunting rights or environmental justice, or the degree to which the pipeline’s effects are likely to be highly controversial.”

The Corps’ decision allowing the pipeline to cross under the Missouri River half a mile upstream from the Standing Rock Reservation—made on Feb. 3, just two weeks after President Donald Trump took office—was “devoid of any discussion” of the evidence of risk that the tribe had submitted, the judge wrote.

“The Court cannot conclude that the Corps made a convincing case of no significant impact or took the requisite hard look,” he said.

Boasberg did not immediately rule on whether the flow of oil, which started through the pipeline on June 1, should be stopped. He wrote that a decision on that “will be the subject of further briefing.”

The pipeline’s construction spurred months of protests and dozens of arrests over its location near the Standing Rock Reservation and particularly its crossing under the Missouri River at Lake Oahe, the tribe’s water supply and an area it considers sacred.

The tribe filed suit in July 2016 after the Corps concluded that a cursory environmental assessment of the pipeline project was sufficient and released a finding of no significant impact. At the time, the Obama Interior Department and Environmental Protection Agency both raised concerns about the lack of a full environmental impact statement—a more rigorous level of review. The EPA said the Corps’ assessment did not sufficiently consider the impacts on water resources, and the Corps later agreed to that more in-depth review.

“As we all know,” Boasberg wrote, “elections have consequences, and the government’s position on the easement shifted significantly once President Trump assumed office.”

In one of his first acts as president, Donald Trump issued a presidential memorandum directing the Corps to expedite the pipeline’s approval.  

Boasberg’s decision on Wednesday was not an outright victory for Standing Rock. The judge found that the Corps’ decision not to issue a detailed environmental impact statement “largely complied” with the law. But the exceptions were substantial, he said, including the Corps’ failure to offer “any acknowledgment of or attention to the impact of an oil spill on the Tribe’s fishing and hunting rights.”

The Corps had dismissed the tribe’s concerns summarily, pointing to the project’s “state-of-the-art construction techniques” and “use of high quality materials and standards.” “There will be no direct or indirect effects to the Standing Rock Sioux Tribe,” the Corps said in its environmental assessment.

But Boasberg said the Corps was looking only at the project’s construction, not the potential for a spill. Furthermore, the treatment fell short of the Corps’ duty to determine whether the project would have a disproportionate impact on minority and low-income populations, as the agency is required to do by law. Boasberg cited Council on Environmental Quality guidance on environmental justice, and case law under the National Environmental Policy Act.

The Corps, in its decision, “is silent, for instance, on the distinct cultural practices of the Tribe and the social and economic factors that might amplify its experience of the environmental effects of an oil spill,” Boasberg said. “Standing Rock provides one such example in its briefing: many of its members fish, hunt, and gather for subsistence. Losing the ability to do so could seriously and disproportionately harm those individuals relative to those in nearby nontribal communities.

“The Corps need not necessarily have addressed that particular issue, but it needed to offer more than a bare-bones conclusion that Standing Rock would not be disproportionately harmed by a spill,” the judge said.

The pipeline’s builder, Dakota Access LLC, part of Energy Transfer Partners, has already faced leaks along the pipeline. It also has drawn criticism for lacking a detailed oil spill response plan for the section of pipe that crosses the Missouri River. 

Jan Hasselman, an attorney with Earthjustice, an environmental law firm that represents the tribe, said the decision marks an important turning point.

“Until now, the rights of the Standing Rock Sioux tribe have been disregarded by the builders of the Dakota Access pipeline and the Trump administration—prompting a well-deserved global outcry,” Hasselman said. “The federal courts have stepped in where our political systems have failed to protect the rights of Native communities.”

Trump has repeatedly cited the Dakota Access project start as proof of his administration’s progress on lifting government restrictions on development. The $3.8 billion, 1,200-mile pipeline project, designed to transport oil from the Bakken Shale fields of North Dakota to refineries, was more than 90 percent complete when the Obama administration began its expanded environmental review.

“Nobody thought any politician would have the guts to approve that final leg,” Trump said at a June 7 speech on his infrastructure plan. “And I just closed my eyes, and said, ‘Do it,'” he said.

“It’s up, it’s running, it’s beautiful, it’s great, everybody’s happy, the sun is still shining, the water is clean,” he said. “But you know, when I approved it, I thought I’d take a lot of heat. And I took none. Actually, none. People respected that I approved it.”

But Boasberg’s ruling makes clear that Trump’s signature was not the final word on the Dakota Access pipeline.