The U.S. has no plans to mediate a spat between Japan and South Korea, which are locked in a dispute over history and trade, an American official said in an interview with public broadcaster NHK.

David Stilwell, the U.S. assistant secretary of state for East Asian and Pacific Affairs, told NHK that he would only encourage both sides to focus on key regional issues and in particular North Korea. Stilwell is on his first visit to Japan since his appointment last month.

"I encourage both sides to sit down and talk and find a positive way out of the situation," he said.