WASHINGTON (AP) — The director of the federal Bureau of Indian Affairs has resigned after six months on the job.

A spokeswoman says Bryan Rice, a veteran federal administrator and citizen of the Cherokee Nation of Oklahoma, resigned earlier this week. Interior Secretary Ryan Zinke named Rice to the post in October.

BIA spokeswoman Nedra Darling did not offer a reason why Rice resigned and declined further comment.

She said Darryl LaCounte will serve as acting BIA director. She called him an experienced leader who will “maintain a smooth transition” for BIA employees and tribal nations.

The BIA coordinates government-government relations with 567 federally recognized tribes in the United States.

Rice previously led Interior’s Office of Wildland Fire and also has worked for the U.S. Forest Service, an Agriculture Department agency.