washington u.s. president donald trump strategy north korea aim pressure pyongyang dismantle nuclear ballistic missile program tighten sanction washington open negotiations trump administration say wednesday u.s. stance appear signal willingness exhaust non-military options put forward statement follow unusual white house-hosted brief entire senate describe north korea urgent national security threat top foreign policy priority unite state seek stability peaceful denuclearization korean peninsula remain open negotiations towards goal say joint statement secretary state rex tillerson defense secretary jim mattis director national intelligence dan coat however remain prepare defend ally although statement emphasize diplomacy democratic senator christopher coons tell reporters white house brief military options discuss sober brief clear much think plan go prepare military options call diplomatic strategy strike clear-eyed well proportion coons say u.s. say strategy north korea center sanction open talk