washington/seoul saddle tough job american diplomacy chief u.s. negotiator north korea stand u.s. president insist want talk enemy show interest listen veteran state department asia hand joseph yun might washington best diplomatic hope reduce risk devastate war korean peninsula serve administration rive divisions handle pyongyang side north korea young leader kim jong un show little interest negotiate either least develop nuclear-tipped missile capable hit u.s. mainland despite daunt obstacles south korean-born yun tell colleagues others hop diplomatic efforts low temperature dangerous nuclear stand-off accord reuters interview dozen current former u.s. officials south korean diplomats deeply skeptical chance dreamer white house official say note sarcasm think go anywhere say another u.s. official although suggest still worthwhile keep engage level north koreans long yun appear undermine president donald trump public rejection direct negotiations trump tell aid military threats drive north korea capitulate rein nuclear missile program four white house officials say view share among u.s. intelligence agencies yun however quietly pursue direct diplomacy north korean officials unite nations mandate discuss issue beyond release u.s. citizens senior state department official tell reuters week june secure release u.s. student otto warmbier return unite state coma die days late trump head asia friday senior aide warn world run time north korea crisis behind scenes yun try keep open fragile line communication could use prevent miscalculation one side spiral military conflict aggravate tensions two u.s. strategic bombers conduct drill south korea thursday follow word south korea spy agency north korea may prepare another missile launch u.s. officials say privately intercept test missile among options consideration though disagreement within administration risk midst yun soft-spoken 32-year foreign service veteran take job year ago near end obama administration grapple trump strident rhetoric well disagreement among president top aid whether saber-rattling force kim capitulate threshold military action accord several u.s. officials speak condition anonymity concern yun difficulties surface seoul visit regularly trump travel next week second stop asian tour several south korean officials express worry yun diplomatic efforts north korea lack real underpin support white house things clearly easy one south korean diplomat say yun precisely person talk north korea trump kill whole process secretary state rex tillerson tell reporters sept. 30 unite state probe diplomatic open slap trump tell via twitter waste time time cia director mike pompeo regularly brief trump intelligence matter consider one hawkish voice north korea president inner circle apparently gain stature several officials familiar discussions say pompeo feed trump assessments u.s. military threats force kim bow u.s. demand nuclear disarmament position u.s. intelligence officer privately contest cia decline comment u.s. official speak condition anonymity say yun become diplomatically untethered fully connect core u.s. approach emphasize economic sanction threat military action rather diplomacy one tangible achievement yun diplomatic efforts past year win release 22-year-old warmbier secret talk north korean officials oslo new york yun fly pyongyang june medically evacuate warmbier choe son hui head north korean foreign ministry north america bureau meet yun oslo unaware serious warmbier condition source washington knowledgeable matter say learn shock yun summon urgently meet north korean diplomat new york quickly lead warmbier return home source say warmbier death complicate yun efforts contribute chill u.s.-north korean contact around time state department official say despite trump threats military action pyongyang state department official say yun view less engage diplomatically likely dark even trump rhetoric raise question among ally possibly even north korea serious administration diplomacy much mandate yun may pursue trump personalize conflict deride kim little rocket man advice national security intelligence experts warn could counterproductive senior national security official say another official point however trump may say would honor meet kim hurl fresh insult kim recent days raise hop alter approach south korean official seoul say necessary washington someone contact north korea help spur future negotiations ever take hold trump national security adviser h.r mcmaster tell japan nhk television week afford enter long drawn-out negotiations allow north korea use negotiations cover continue nuclear missile program former u.s. negotiators sympathize yun whose authority negotiate undercut tug-of-war white house breathe fire state department push peaceful solution nobody doubt authority say wendy sherman one lead u.s. negotiators achieve 2015 deal iran agree restrain nuclear program return relief economic sanction undermine ability job robert gallucci chief u.s. negotiator north korean nuclear crisis 1994 recent contact yun say envoy realistic challenge negotiate current atmosphere include tone set president believe mission even approach guide realism 'he 's dreamer skepticism dog u.s. envoy 's north korean peace efforts