A federal appeals court panel had tough questions for opponents of the $3.8 billion, four-state Dakota Access oil pipeline who are arguing to keep a temporary stop of construction in place.

The three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit heard arguments Wednesday in the Standing Rock Sioux Tribe's request to continue blocking work on a section of the approximately 1,200-mile pipeline near Lake Oahe while the tribe seeks to appeal a lower-court ruling from September.

The pipeline, which runs through North Dakota, South Dakota, Iowa and Illinois, is otherwise nearly complete.

The tribe says the pipeline, being built by Dallas-based Energy Transfer Partners, will impact sites of historic, religious and cultural significance.

The judges didn't say when they'd rule.