The US Secretary of State Rex Tillerson has said the situation in northern Myanmar - also known as Burma - constitutes an 'ethnic cleansing' against Rohingya Muslims.
Burmese police and army launched a violent crackdown in the northern Rakhine state following attacks by Rohingya insurgents on police posts in August.
It is believed that thousands of people in the state have been killed or tortured by security forces, while human rights groups have documented partial or total destruction of Rohingya villages.
According to the United Nations, an estimated 620,000 Rohingya refugees have fled to Bangladesh since August 25th as a result of the violence.
Mr Tillerson visited Myanmar earlier this month, and met with the country's de facto leader Aung Sang Suu Kyi - the Nobel Peace Prize winner who has faced international criticism for her response to the crisis.
While he indicated during the visit that the US was still evaluating whether they should use the term 'ethnic cleansing', Mr Tillerson has now adopted the stronger language to describe the "difficult and complex" situation in Myanmar.
In a statement released today, the top US diplomat said: "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 to seek refuge in Bangladesh.
"After a careful and thorough analysis of available facts, it is clear that the situation in northern Rakhine state constitutes ethnic cleansing against the Rohingya."
He stated that those responsible 'must be held accountable', reiterating that the US supports a 'credible, independent' investigation into the situation.
Mr Tillerson added: "We support the Burmese government’s commitment to create the conditions necessary for all refugees and internally displaced people to return to their homes safely and voluntarily, and welcome recent exchanges between the governments of Burma and Bangladesh on repatriation.
"Support by Burma’s military for these government efforts is crucial."
Further clarifying the statement, a senior US State Department official told reporters: "Part of the determination on ethnic cleansing implies a certain intent and planning, so not just isolated incidents. So I think the determination does indicate that we feel it was, again, organised, planned, systematic."
Mr Tillerson also stated that the US will consider measures such as 'targeted sanctions' as part of their response to the situation in Myanmar.