Seoul and Washington agreed a five-year deal on defence cost-sharing last year, but Mr Trump recently indicated that expenses tied to the American military presence could become a point of negotiation in broader trade talks. But South Korean officials insisted on tackling the issue of defence contributions separately.

South Korea hosts the third-largest number of American troops outside the U.S.—after Japan and Germany—stationed there to help defend Seoul against threats from nuclear-armed North Korea and support regional efforts to counter an increasingly assertive China.