WASHINGTON (AP) – President Donald Trump has signed an executive order Tuesday morning to advance construction of the Dakota Access and Keystone XL oil pipelines.

The Army decided last year to explore alternate routes for the Dakota Access pipeline after the Standing Rock Sioux tribe and its supporters said the pipeline threatened drinking water and Native American cultural sites. The pipeline is to carry North Dakota oil through South Dakota and Iowa to a shipping point in Illinois.

Former President Barack Obama killed the proposed Keystone XL pipeline in late 2015, declaring it would have undercut U.S. efforts to clinch a global climate change deal. The pipeline would run from Canada to U.S. refineries in the Gulf Coast. The U.S. government needed to approve the pipeline because it crossed U.S. border.