Song Sang-hyun said "the time is right" for Ukraine to file a complaint over North Korea's military assistance to Russia.

On Wednesday, local media were given access to the Korea Air and Space Operations Center (KAOC), a highly secured command post located within Osan Air Base in Pyeongtaek, about 60km south of Seoul.

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.

South Korea's defense ministry said Friday it has not held any discussions with the Pentagon over the possibility of scaling back U.S. Forces Korea (USFK) troops stationed in South Korea. The remark came in response to a report by The Wall Street Journal that U.