dhaka u.s. government constantly monitor sanction regime respond violence myanmar rakhine state send hundreds thousands rohingya muslim refugees across border bangladesh senior u.s. official say saturday constantly evaluate situation simon henshaw act assistant secretary state bureau population refugees migration tell reporters news brief dhaka visit camp cox bazar hundreds thousands rohingya refugees shelter congress give us number tool use say note disturb report atrocities rakhine state call full investigation report call commit atrocities hold accountable say incredible within two months 600,000 refugees take shelter country seven-member delegation lead henshaw visit myanmar oct. 29 travel bangladesh wednesday go cox bazar thursday meet myanmar government officials tell responsibility return secure stable situation rakhine state also responsibility investigate report atrocities delegation also ask myanmar allow rohingya people back land rehabilitate villages burn say shock rohingya account atrocities murder sexual assault delegation call myanmar government allow access press international organizations could see situation grind say u.s. state department spokeswoman heather nauert say issue take high level authority u.s. government statements relate situation myanmar issue white house also state department say delegation would update u.s. secretary state rex tillerson visit myanmar nov. 15 2,500 rohingya refugees cross bangladesh friday two border cross senior security official say saturday refugees already send different camp supervision bangladesh army major mohammad iqbal deputy command officer bangladesh border guard cox bazar district tell reuters u.s. monitor sanction regime response myanmar situation official