During his visit to the region last week, Tillerson stressed that Myanmar's response to the crisis would be vital to determining the success of its transition to becoming "a more democratic society" and that those responsible for such human rights abuses must be held accountable.
More than 600,000 Rohingya have fled the mainly Buddhist country since the military launched a counter-insurgency operation in Rakhine state in late August, heading to neighbouring Bangladesh, which is one of the world's poorest countries.
The United States on Wednesday toughened its stance on Myanmar, accusing the country's security forces of perpetrating "horrendous atrocities" against the Rohingya that amount to "ethnic cleansing" of the Muslim minority.
While the army insists it has only targeted Rohingya rebels, refugees massing in Bangladeshi camps have given chilling and consistent accounts of widespread murder, rape and arson at the hands of security forces and Buddhist mobs.
US Senator John McCain, who chairs the Senate Armed Services Committee, welcomed Tillerson's statement as a first step that should be followed by "targeted sanctions against the military officials responsible for these atrocities". USA officials dangled the possibility of an "ethnic cleansing" designation ahead of Tillerson's trip, potentially giving him more leverage as he met with officials in Myanmar.
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However, senior administration officials ruled out a broad based sanctions against Myanmar, noting that the democracy in the country is in its nascent stage. Appearing alongside de facto leader Aung San Suu Kyi, Tillerson said more information was needed before the United States aligned itself with the United Nations, which has condemned Myanmar's treatment of the Rohingya.
British Prime Minister Theresa May's spokesman said on November 13 the actions of the military in Rakhine State "looks like ethnic cleansing", adding it was a "major humanitarian crisis".
Speaking of "abuses" that had occurred, Tillerson said the United States would consider targeted sanctions against those responsible.
"The determination does indicate we feel it was. organized planned and systematic", a senior USA official told reporters on a conference call.
Broad-based USA sanctions on Myanmar were eased under former President Barack Obama as the Southeast Asian nation inched toward democracy. USA officials also worry that the mistreatment of the Rohingya Muslim minority may fuel radicalism. That could slow or reverse the country's delicate transition away from decades of harsh military rule and risks pushing Myanmar away from the US and closer to China. Both designations carry significant legal consequences. The ethnic cleansing term surfaced in the context of the 1990s conflict in the former Yugoslavia, when a United Nations commission defined it as "rendering an area ethnically homogeneous by using force or intimidation to remove persons of given groups from the area".
Two months earlier, just a few weeks after the violence erupted, UN Human Rights Chief Zeid Ra'ad Al Hussein said Myanmar's military operation was a "textbook example of ethnic cleansing". Almost one million Rohingya have been forced to leave their homes, many fleeing to neighboring Bangladesh. In 1982, they were stripped of their citizenship. Earlier this year, the USA restored restrictions on granting visas to members of Myanmar's military, and the State Department has deemed units and officers involved in operations in Rakhine state ineligible for US assistance. "The time for outrage and condemnation has passed".