The US Army was ordered to permit the building of the last segment of a controversial oil pipeline.
North Dakota Senator John Hoeven said the Army Corps of Engineers was directed to permit work a reservoir on the Missouri River, under Lake Oahe.
Native Americans, who’ve protested against the Dakota Accessibility Pipeline for months, vowed legal action to prevent it.
President Donald Trump recently signed an executive order indicating his support.
The US Army Corps of Engineers, which includes approval power, determined a year ago to investigate other paths for the pipeline by the Standing Rock Sioux Tribe amid huge demonstrations.
In a statement on Tuesday, Mr Hoeven stated the temporary Secretary of the Army, Robert Speer, had ordered the corps to permit the work required to finish the pipeline.
“The Army Corps lacks statutory power to just quit the EIS,” they said in a statement.
The Sioux say the last section damage holy burial sites and would contaminate drinking water. Their assistants and they have set up a Holy Stone religious camp close to the Missouri river.
He told the Army to immediately reconsider its choice to investigate other paths.