WASHINGTON — A federal judge temporarily blocked construction of the controversial Keystone XL pipeline, ruling late Thursday that the Trump administration had failed to justify its decision granting a permit for the 1,200-mile-long project designed to connect Canada’s tar sands crude with refineries on the Texas Gulf Coast.

It was a major defeat for President Donald Trump, who attacked the Obama administration for failing to move ahead in the face of protests based largely on environmental concerns. Trump signed an executive order two days into his presidency setting in motion a course reversal on the Keystone XL pipeline and the Dakota Access pipeline.

The decision, issued by Judge Brian Morris of the U.S. District Court for the District of Montana, does not permanently block a permit but requires the administration to conduct a more complete review of potential adverse impacts related to climate change, cultural resources and endangered species.

Morris hit the administration with a familiar charge, that it disregarded facts established by experts during the Obama administration about “climate-related impacts” from Keystone XL. The administration claimed, with no supporting information, that those impacts “would prove inconsequential.” The State Department “simply discarded prior factual findings related to climate change to support its course reversal.”

It also used “outdated information” about the impact of potential oil spills on endangered species, he said.

On the South Lawn of the White House on Friday and before departing for Paris, Trump denounced the decision, saying, “It was a political decision made by a judge. I think it’s a disgrace.”

“Today’s ruling makes it clear once and for all that it’s time for TransCanada to give up on their Keystone XL pipe dream,” said Sierra Club Senior Attorney Doug Hayes in a statement. The lawsuit prompting Thursday’s order was brought by a collection of opponents, including the indigenous Environmental Network and the Northern Plains Resource Council, a conservation coalition based in Montana.

“The Trump administration tried to force this dirty pipeline project on the American people, but they can’t ignore the threats it would pose to our clean water, our climate, and our communities,” Hayes said.

Hayes told The Washington Post that the company had already been moving equipment into place with the intent of beginning construction in early 2019.

“It’s clear that this decision tonight will delay the pipeline significantly,” said Hayes, who noted that a proper environmental impact statement of this scope usually takes about a year to complete. “TransCanada does not have an approved pipeline at this point.”

Morris, a former clerk to the late Chief Justice William Rehnquist, was appointed to the bench by President Barack Obama.

No immediate comment came from the administration after the pipeline order on whether it would appeal Thursday’s ruling. TransCanada, the Calgary-based group behind the project, did not respond to request for comment Friday.

The pipeline is intended to be an extension of TransCanada’s existing Keystone Pipeline, which was completed in 2013. Keystone XL would transport up to 830,000 barrels of crude oil per day from Alberta, Canada, and Montana to Oklahoma and the Gulf Coast. In the U.S., the pipeline would stretch 875 miles through Montana, South Dakota and Nebraska, with the rest continuing into Canada.

It met sustained opposition from environmental advocacy groups, as well as skepticism from Obama, who worried about the contribution it would make toward climate change.

In 2015, on the eve of the international climate talks in Paris, the Obama administration appeared to bring an end to the seven-year-long saga when it announced it was halting construction of the pipeline, arguing that approval would compromise the country’s effort to reduce its greenhouse gas emissions. The U.S., Obama said, was now a “global leader when it comes to taking serious action to fight climate change.”