The Pebble project has been through a roller coaster of regulations for the past 15 years. Former U.S. President Barack Obama opposed the project, and his successor Donald Trump ultimately did, too, after deciding it was too risky.

President Joe Biden has also long opposed the project and took steps upon taking office in 2021 to permanently protect Alaska's Bristol Bay.

In January the U.S. Environmental Protection Agency said it plans to take steps to block the proposed Pebble project by preventing Northern Dynasty from storing mine waste in the state's vast watershed.

(Reporting by Arunima Kumar in Bengaluru; editing by Eileen Soreng)