The state of Alaska is halting plans to kill wolves on caribou calving grounds in a national refuge until a federal judge rules on the matter.

The Alaska Department of Fish and Game had said the mission on Unimak Island in the Aleutians could begin as early as Tuesday. But Department of Law spokesman Bill McAllister says the hope now is to resolve the issue in court.

State game officials want to kill predators on Unimak from the air to remove wolves preying on caribou calves and help the herd make a comeback.

But the U.S. Fish and Wildlife Service wants more time to assess the situation. It has threatened to consider state employees trespassers on the refuge.

The state sued the Fish and Wildlife Service last week, seeking a temporary restraining order.