The Biden administration has declared that Myanmar’s military has committed genocide against the Rohingya minority.
The US has seen evidence pointing to a clear intent to destroy the Rohingya, with reports of killings, mass rape and arson, Secretary of State Antony Blinken said on Monday.
Hundreds of thousands of Rohingya Muslims have fled Myanmar since the military crackdown that began in 2017.
More than 6,000 people were killed in the first month of the onslaught.
Speaking at the United States Holocaust Memorial Museum in Washington DC, Mr Blinken called the attacks against Rohingya “widespread and systematic”.
He said said the administration’s determination was based on a review by the US state department that included documents gathered by organisations like Amnesty International and Human Rights Watch, as well as independent research by the US.
Mr Blinken announced the US would provide $1m (£758,000) in new funding for the Independent Investigative Mechanism for Myanmar, which continues to examine atrocities.
A case against Myanmar, also called Burma, was opened at the International Court of Justice in 2019.
“The day will come when those responsible for these appalling acts will have to answer for them,” Mr Blinken said.
A civilian government was in charge when the military launched its campaign, but in 2021 the military took power in a coup. Mr Blinken said that since the coup, the military continues to use the same tactics.
“For those who did not realise it before the coup, the brutal violence unleashed by the military since February 2021 has made clear that no one in Burma will be safe from atrocities so long as it is in power,” he said.
The Rohingya, who numbered about one million in Myanmar before the attacks on them, are one of the many ethnic minorities in the country.
Rohingya Muslims represent the largest percentage of Muslims in Myanmar, with the majority living in Rakhine state.
But the government of Myanmar, a predominantly Buddhist country, denies the Rohingya citizenship and even excluded them from the 2014 census, refusing to recognise them as a people.
When US President Joe Biden took office 14 months ago, Mr Blinken pledged to conduct a fresh review of the issue.
Two previous US investigations failed to reach a conclusion.
A ruling of genocide does not automatically lead to punitive action by the US, but it is hoped it will put pressure on the Myanmar military.
“It’s going to make it harder for them to commit further abuses,” a senior State Department official told Reuters.
There has so far been no comment from the military authorities in Myanmar.