washington/seoul u.s. president donald trump agree principle scrap warhead weight limit south korea missiles wake north korea sixth nuclear test white house say monday call south korean president moon jae-in trump also give conceptual approval south korea buy billions dollars weapons unite state white house say statement separately south korea presidential office say two leaders agree scrap weight limit apply strong sanction pressure north korea unite nations separate phone call russian president vladimir putin also monday moon say u.n. security council seek ways sever north korea foreign currency income include workers employ abroad oil shipments accord south korean statement exist missile pact unite state south korea seoul warheads currently face cap 500 kg 1100 lb agreement last amend 2012 process change wake series missile test north korea year moon take office may include two intercontinental ballistic missile launch north korea say test advance hydrogen bomb long-range missile sunday prompt global condemnation u.s. warn massive military response ally threaten unlimited warhead weight allowance would enable south strike north korea great force event military conflict missiles would still bind flight range cap 800 km change flight range mention blue house statement analysts policymakers agree cut supply oil north korea would hurt economy remain see whether china north big ally trade partner would cooperate south korea say early day talk unite state deploy aircraft carriers strategic bombers korean peninsula sign north korea might launch missiles trump agree 'in principle scrap south korean warhead weight limit white house