WASHINGTON – In an abrupt reversal, the Pentagon said Thursday it supports a Republican proposal in a defense policy bill that would bar the Fish and Wildlife Service from using the Endangered Species Act to protect two chicken-like birds in the western half of the U.S.

In an email to Congress, a top Pentagon official said the proposal could help avoid any “negative readiness impacts on military facilities” that might result from listing the sage grouse and lesser-prairie chicken as endangered.

The statement by Pete Giambastiani, a legislative affairs aide, directly repudiates comments Wednesday by Pentagon officials calling the GOP proposal unnecessary. The House-approved language would block endangered-species listing for the two birds for 10 years.

The birds have become flashpoints in an ongoing battle over whether they warrant federal protection that hinders mining and other development from Kansas to California.

In a one-paragraph position paper made public Wednesday, the Pentagon said the GOP provision was “not necessary to protect military testing and training” and said the department “urges its exclusion” from the defense bill being negotiated by House and Senate leaders.

Lucian Niemeyer, assistant secretary of defense for energy, installations and environment, said Wednesday that military installations are “not experiencing significant mission impacts related to the management” of the sage grouse, lesser-prairie chicken or the American burying beetle, another threatened species targeted by the GOP bill.

Giambastiani, in his email Thursday, challenged the accuracy of Niemeyer’s statement.

“The administration, the Defense Department and the Interior Department support the provision in question and believe that it could help the department avoid any negative readiness impacts on military facilities should the species be listed as endangered under the Endangered Species Act,” he wrote. “Importantly, several vital military installations are impacted by sage grouse populations in, around or underneath the airspace used by the Department of Defense on a daily basis.”

Alex Thompson, a spokeswoman for the Wilderness Society, said the GOP bill would “undermine collaborative, bipartisan efforts of Western states and federal agencies by binding the hands of federal agencies to exercise authority under the Endangered Species Act” to protect the sage grouse and lesser-prairie chicken.

“This attempted end-run around congressional authorizing committee jurisdictions has drawn furious opposition” from veterans and sportsmen groups across the country, Thompson said, vowing to fight against the GOP plan.

Utah Rep. Rob Bishop inserted the endangered-species language into the defense policy bill, arguing that federal conservation efforts for the imperiled birds and the beetle undermine military training and readiness.

A 2015 report by the Army says land-use restrictions designed to protect the sage grouse could affect operations at a number of Western sites, including the Yakima Training Center in Washington state and Hawthorne Army Depot in Nevada.