Washington formally determined Tuesday that Myanmar's military carried out a coup, legally requiring an end to US assistance to the government.
"We have assessed that the Burmese military's actions on February 1, having deposed the duly elected government, constituted a military coup d'etat," State Department spokesman Ned Price told reporters, using Myanmar's former name of Burma.
"The United States will continue to work closely with our partners throughout the region and the world to support respect for democracy and the rule of law in Burma," added said.
Under US law, the United States will be forbidden from assisting the government but the effects will be largely symbolic as virtually all assistance in Myanmar goes to non-governmental channels.
Asked how much money goes through the government, Price said it was a "very small portion."
The military was already under US sanctions over its brutal campaign against the Rohingya minority.
The State Department said Washington would maintain humanitarian programs, including for the Rohingya, but will also undertake a broader review of our assistance to Myanmar.
President Joe Biden in a forceful statement Monday said the US would consider reimposing sanctions on Myanmar, which were lifted during its decade-long transition to democracy.
Washington has contributed $1.5 billion to Myanmar since 2012 to support democracy, internal peace and violence-hit communities, according to the State Department.
Another State Department official, briefing reporters on customary condition of anonymity, said that the United States has had no contact since the coup either with the military or civilian leaders, who have been put under house arrest.
But the official said that the United States is "having daily ongoing conversations" with Japan and India, close US partners that "have better contact with the Burmese military than we do."
Japan and India, both eager to offer an alternative to Myanmar's major partner China, have pursued cordial relations even after Western nations pulled back over the treatment of the Rohingya, on which Aung San Suu Kyi said little.
Days before the coup, India shipped 1.5 million doses of Covid-19 vaccine to Myanmar.