SEOUL, South Korea (AP) — The top diplomats from South Korea, Japan and China met Sunday to discuss when to resume their leaders’ trilateral summit after a four-year hiatus and how to strengthen cooperation among the three Northeast Asian neighbors.

Closely linked economically and culturally with one another, the three countries together account for about 25% of the global gross domestic product. But efforts to boost trilateral cooperation have often hit a snag because of a mix of issues including historical disputes stemming from Japan’s wartime aggression and the strategic competition between China and the United States.