Federal Judge Brian Morris has refused a request to stop construction of the controversial Keystone XL tar sands pipeline project.

The Assiniboine and Gros Ventre tribes of the Fort Belknap Indian Community in Montana and Rosebud Sioux Tribe in South Dakota have long challenged President Donald Trump's 2019 permit for the Keystone.

The tribes say Trump’s permit violates their rights under treaties from the mid-1800s.  They also fear damage to sacred cultural sites in the event of a pipeline leak, as the pipeline's trajectory takes it directly over areas where the Indians live: almost 35,000 members, many of whom reside in the area that will be crossed by the Pipeline, including in Tripp County, South Dakota.

The Fort Belknap Indian Community of Montana and the Rosebud Sioux Tribe of South Dakota contend there was no effort to study how the 1,200-mile pipeline project through their respective territories would affect their water systems and sacred lands.

While Morris said he had “serious questions" about the legal claims being made by the tribes, he did not make a final ruling and invited further arguments.

Nonetheless, much of the work on Keystone XL remains stalled, as the U.S. Supreme Court in July upheld a lower court ruling that invalidated a permit needed for the pipeline to cross hundreds of rivers and other water bodies along its route.