unite nations unite nations political affairs chief jeffrey feltman say tuesday senior north korean officials offer type commitment talk visit pyongyang last week believe leave door ajar feltman highest-level u.n. official visit north korea since 2011 meet foreign minister ri yong ho vice minister pak myong guk four-day visit describe important mission ever undertake time tell impact discussions think leave door ajar fervently hope door negotiate solution open wide feltman tell reporters brief u.n. security council behind close doors visit need time digest consider respond message say add believe ri would brief north korean leader kim jong un discussions u.s. secretary state rex tillerson offer tuesday begin direct talk north korea without pre-conditions back away u.s. demand pyongyang must first accept negotiations would give nuclear arsenal feltman say ask north korea signal prepare consider engagement like possible talk talk open technical channel communication military-to-military hotline reduce risk signal intentions prevent misunderstand manage crisis listen seriously arguments ... offer type commitment us point say feltman agree important prevent war ... topic 15-plus hours discussions say unite nations could act facilitator north korea pursue nuclear missile weapons program defiance u.n. sanction international condemnation nov. 29 test-fired intercontinental ballistic missile say advance yet capable reach mainland unite state feltman describe visit constructive productive say north koreans agree continue dialogue people meet listen carefully arguments explore think ask question argue us ultimately take say talk internally talk leadership say north korea would commit peace talk 'door ajar u.n. envoy