"With this project authorization, we've begun winter construction," CEO Ryan Lance said.
Environmental and indigenous groups in November asked a federal court in Alaska to temporarily bar ConocoPhillips from going forward with construction of the project in the state's Arctic, arguing a stay is necessary to stop imminent cultural and environmental harms.
The Willow project area holds an estimated 600 million barrels of oil, and ConocoPhillips has said the project will produce up to 180,000 barrels of oil per day at its peak.
The project development has been backed by Alaskan officials, who are hoping it will help offset oil production declines in a state whose economy relies heavily on the oil and gas industry.
