washington secretary state rex tillerson say sunday president donald trump instruct continue diplomatic efforts calm rise tensions north korea say diplomatic efforts continue first bomb drop speak cnn state union tillerson downplay message president trump previously post twitter suggest tillerson waste time try negotiate little rocket man derogatory nickname trump coin north korea leader kim jong un trump make clear continue diplomatic efforts tillerson say tillerson comment sunday come amid soar tensions unite state north korea follow series weapons test pyongyang war word two countries leaders north korea conduct series nuclear test recent weeks ago launch two missiles japan tillerson talk china enlist help get north korea back trump recent twitter message appear undercut tillerson efforts prompt senate foreign relations committee chairman bob corker complain trump publicly castrate tillerson hurt diplomatic talk tillerson downplay tweet sunday tell cnn trump china president xi jinping extremely close relationship china understand u.s. position rest assure chinese confuse way american policy towards north korea add u.s. diplomacy north korea continue 'first bomb drop tillerson