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.