Caribou from the Porcupine Caribou Herd migrate onto the coastal plain of the Arctic National Wildlife Refuge in northeast Alaska. The refuge has long been eyed for oil exploration.

FILE – In this undated file photo provided by the U.S. Fish and Wildlife Service, caribou from the Porcupine Caribou Herd migrate onto the coastal plain of the Arctic National Wildlife Refuge in northeast Alaska. Opponents of petroleum drilling in Alaska’s Arctic National Wildlife Refuge are preparing for a response to a possible petroleum lease sale. The Interior Department hopes to conduct a lease sale by the end of 2019. (U.S. Fish and Wildlife Service via AP, File)