Washington "will do what it can do" to help defuse a political and economic dispute between its allies South Korea and Japan, the top U.S. diplomat responsible for Asia policy said.

David Stilwell, U.S. assistant secretary of state for Asian and Pacific affairs, was in Seoul for a multi-day visit. Washington has been hesitant to become involved in the dispute, and Stilwell did not say what steps the United States would be willing to take.

South Korea and Japan are locked in a dispute ranging from Japan's wartime use of forced labour to trade curbs that threaten to disrupt global supplies of memory chips and smartphones.