Former U.S. Energy Secretary Rick Perry has rejoined the board of the company that oversees Energy Transfer Partners, one of the biggest pipeline operators in the United States. The company, owned by billionaire Kelcy Warren, is best known for its Dakota Access crude oil pipeline, the construction of which drew months of massive resistance led by the Standing Rock Sioux and other Native American nations. Perry had previously served as a director of Energy Transfer Partners before stepping down in 2016 as the corporation faced backlash over the Dakota Access pipeline.