The White House has blocked new leases for oil and gas drilling in sections of the Arctic and Atlantic, which is a high-stakes bid to forestall exploration and tie Donald Trump's hands. The protection covers an area of the Arctic, roughly the size of Spain or Thailand, and 31 sea canyons in the Atlantic. A senior administration official said that there was a "strong legal basis" for the move, and suggested Trump could not revoke the decision without an act of Congress. The move, based on a law from the 1950s, was taken in tandem with the Canadian government. Obama said in a statement that the measures would "protect a sensitive and unique ecosystem." He also warned that the risk of oil spills "are significant," and the ability "to clean up from a spill in the region's harsh conditions is limited." The Hawaii-born president's second year in office was dominated by the catastrophic Deepwater Horizon oil spill, which poured millions of barrels of oil into the Gulf of Mexico. The spill could not be stopped for 87 days, devastating wildlife and fishing-dependent communities in Louisiana, Mississippi, Florida, and Alabama.