US president Donald Trump has signed executive actions to advance the construction of the Keystone XL and Dakota Access oil pipelines.
Mr Trump told reporters in the Oval Office that the moves on the pipelines will be subject to terms and conditions being renegotiated by the US government.
Former president Barack Obama blocked the proposed Keystone XL pipeline in late 2015, saying it would hurt American efforts to reach a global climate change deal.
The pipeline would run from Canada to US refineries on the Gulf Coast. The US government needs to approve the pipeline because it crosses the American border.
The Army decided last year to explore alternate routes for the Dakota pipeline after the Standing Rock Sioux tribe and its supporters said the pipeline threatened drinking water and Native American cultural sites.