Conservationists who say wolves remain imperiled after coming back from near-extinction last century blasted the decision, complaining that Idaho and Montana have approved increasingly aggressive wolf-killing measures including trapping, snaring and months-long hunting seasons.

“We are disappointed that the U.S. Fish and Wildlife Service is refusing to hold the states accountable to wolf conservation commitments they made a decade ago,” said Susan Holmes, executive director of the Endangered Species Coalition.

Antipathy toward wolves for killing livestock and big game dates to early European settlement of the American West in the 1800s, and it flared up again after wolf populations rebounded under federal protection. That recovery has brought bitter blowback from hunters and farmers angered over wolf attacks on big game herds and livestock. They contend protections are no longer warranted.