naypyitaw u.s. secretary state rex tillerson call wednesday credible investigation report human right abuse rohingya muslims commit myanmar security force meet civilian military leaders 600,000 rohingya muslims flee bangladesh since late august drive military counter-insurgency clearance operation buddhist-majority myanmar rakhine state top u.n. official describe military action textbook case ethnic cleanse deeply concern credible report widespread atrocities commit myanmar security force vigilantes unrestrained security force recent violence rakhine state tillerson tell joint news conference aung san suu kyi head civilian administration less two years old share power military tillerson early hold separate talk myanmar military chief senior general min aung hlaing whose force accuse atrocities senior u.n. official sunday level allegations mass rape kill torture myanmar military know tatmadaw tour refugee camp cox bazar region neighbor bangladesh tillerson call myanmar government lead credible impartial investigation say commit abuse hold responsible recent serious allegations abuse rakhine state demand credible impartial investigation commit human right abuse violations must hold accountable say meet call myanmar civilian government lead full effective independent investigation military facilitate full access cooperation also say duty military help government meet commitments ensure safety security people rakhine state post min aung hlaing facebook page say myanmar military supremo explain tillerson true situation rakhine reason muslims flee military work government deliver aid progress make repatriation process agree bangladesh military launch clearance operation army base 30 police post attack aug. 25 rohingya militants kill dozen members security force tillerson condemn militant attack say response security force need avoid maximum extent possible harm innocent civilians internal investigation military allegations atrocities release week brand whitewash human right group back washington u.s. senators press economic sanction travel restrictions target myanmar military business interest tillerson say would advise broad-based sanction myanmar unite state want see succeed say credible reliable information abuse individuals could target sanction tillerson say unite state would work partner responsible atrocities would face consequences use available mechanisms include available u.s. law myanmar undergo transition democracy decades rule military general retain extensive power security veto reform constitution bar suu kyi presidency myanmar response crisis critical determine success transition democratic society tillerson say responsibility government security force protect respect human right persons within border hold accountable fail say unite state would provide additional 47 million humanitarian assistance refugees bring total 87 million since crisis erupt august humanitarian scale crisis stagger tillerson say say encourage talk myanmar bangladesh agree refugee repatriation process news conference suu kyi ask explain speak strongly plight rohingya nobel peace prize winner perceive failure speak damage international reputation stateswoman say suppose excite suu kyi say add aim keep public inform without set different ethnic religious communities important bring peace stability country do basis rule law everybody understand role protect peace stability punish people tillerson myanmar call credible probe atrocities