SAN FRANCISCO (AP) — A federal appeals court Monday revived a lawsuit that seeks to block construction of a U.S. military base in Okinawa, Japan over concerns about its impact on the Okinawa dugong, an endangered marine mammal that resembles a manatee.

The Center for Biological Diversity has authority to challenge the adequacy of the government's evaluation of the effect on the Okinawa dugong, the 9th U.S. Circuit Court of Appeals said. A three-judge panel of the court also said the environmental group's request for an injunction blocking the project did not raise political questions that were beyond judicial review.

The ruling overturned a 2015 decision by U.S. District Judge Edward Chen in San Francisco that dismissed the suit. The 9th Circuit sent the case back to Chen for further proceedings.

The Department of Justice said in a statement it was reviewing the ruling.

Peter Galvin, director of programs for the Center for Biological Diversity, said the decision was a "lifeline" for the Okinawa dugong.

"The base plan as it's currently conceived is incompatible with the continued existence of the Okinawa dugong," he said.

The legal fight — more than a decade old now — concerns plans to relocate Marine Corps Air Station Futenma to a less dense part of Okinawa.

Environmentalists say the construction of two aircraft runways on landfill in a bay as part of the construction plan will destroy critical feeding grounds and habitat for the Okinawa dugong.

The animal is associated with traditional creation myths in Japan and listed as endangered under the U.S. Endangered Species Act, with its numbers estimated at one point to be below 50.

Japanese officials said in 2012 the project would have no negative effect on the dugong, and U.S. officials reached the same conclusion two years later. But the center said the U.S. review was inadequate.

Construction of the base has begun, though the 9th Circuit said in its ruling there is "no reason to think completion of the base is imminent."

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The name of the Center for Biological Diversity has been corrected in this story.