The U.S. on Wednesday warned it may issue targeted sanctions unless those responsible for "ethnic cleansing" against Rohingya Muslims in Myanmar are held to account.
"Those responsible for these atrocities must be held accountable," Secretary of State Rex Tillerson said in a statement.
He added that the Myanmar government and security forces "must respect the human rights of all persons within its borders and hold accountable those who fail to do so."
For the first time, a U.S. official referred to atrocities committed against the Rohingya in the western state of Rakhine as a "clear" case of "ethnic cleansing against the Rohingya."
A crackdown launched on Aug. 25 has seen more than 620,000 Rohingya cross from Rakhine into Bangladesh, according to the UN.
The refugees are fleeing a military operation that has seen security forces and Buddhist mobs kill men, women and children, loot homes and torch Rohingya villages.
Speaking in September, Bangladeshi Foreign Minister Abul Hasan Mahmood Ali said around 3,000 Rohingya have been killed in the operation.
Referring to an attack on security forces that prompted the Rakhine operation, Tillerson emphasized that "no provocation can justify the horrendous atrocities that have ensued.
"These abuses by some among the Burmese military, security forces and local vigilantes have caused tremendous suffering and forced hundreds of thousands of men, women and children to flee their homes in Burma [Myanmar] to seek refuge in Bangladesh."
- SANCTIONS
In comments to reporters, a State Department official told reporters, on condition of anonymity, that the determination of ethnic cleansing implied the killings were not isolated incidents but were carried out with planning and intent.
"The determination does indicate that we feel it was organized, planned, systematic," the official said, noting that there was "a limited number of groups that can be involved in that planning and organization".
Tillerson's comments follow his visit to Myanmar last week, when he met State Counselor Aung San Suu Kyi and military chief Senior Gen. Min Aung Hlaing.
In both comments in Myanmar and his Wednesday statement, Tillerson condemned the Aug. 25 attacks on security forces that precipitated the crackdown in Rakhine.
Speaking alongside Suu Kyi in capital Nay Pyi Daw, he also ruled out "broad-based economic sanctions against the entire country" but said "targeted sanctions on individuals" credibly implicated in abuses "very well may be appropriate."
Rohingya, described by the UN as the world's most persecuted people, have faced heightened threats of attack since dozens were killed in communal violence in 2012.
Following a similar military crackdown launched in October last year, the UN documented mass gang rapes, killings -- including of infants and young children -- brutal beatings and disappearances committed by security personnel.
UN investigators said such violations may have constituted crimes against humanity.
