The U.S. government plans to appoint Donna Welton, a seasoned diplomat with vast experience in Japan, to lead negotiations over the costs of stationing U.S. forces in the Asian country, sources familiar with the matter said Saturday.

Welton, who has served as political minister-counselor at the U.S. Embassy in Japan and is known for her expertise on Japanese art, will succeed James DeHart as senior adviser for security negotiations and agreements at the U.S. State Department, they said.

DeHart has been the chief negotiator in defense cost-sharing talks with South Korea, but left the post in July. If he had remained, he was expected to have spearheaded the negotiations with Japan, which are likely to start in the fall at the earliest.