The United States has suspended a trade deal with Myanmar until a democratic government is restored in the Southeast Asian country.
The move comes in the wake of a military coup on February 1 that has been followed by a violent crackdown on protests.
The military overthrew the elected government, jailed leader Aung San Suu Kyi and other officials and has killed more than 500 protesters in the country, which is still referred to as Burma in the US.
"The United States supports the people of Burma in their efforts to restore a democratically elected government," US Trade Representative Katherine Tai said in a statement.
"The United States strongly condemns the Burmese security forces' brutal violence against civilians. The killing of peaceful protesters, students, workers, labour leaders, medics, and children has shocked the conscience of the international community."
Tai's office said the United States was immediately suspending "all US engagement with Burma under the 2013 Trade and Investment Framework Agreement".
Under the agreement, the two countries co-operated on trade and investment issues in an effort to integrate Myanmar into the global economy, a reward for the military's decision to allow a return to democracy - a transition that ended abruptly with last month's coup.
Tai's announcement on Monday does not stop all trade between the two countries.
But the United States is separately imposing economic sanctions on Myanmar.
In response to the military takeover, for instance, the US and the United Kingdom had earlier imposed sanctions on two conglomerates controlled by Myanmar's military - Myanmar Economic Holdings and Myanmar Economic Corp.
White House press secretary Jen Psaki noted the US has also slapped export controls on Myanmar and added several of the country's businesses to a trade blacklist.
"We, of course, continue to work with our allies and partners and like-minded institutions, as we condemn the actions of the military, call for the immediate restoration of democracy, and hold those who seize power accountable," she said.
Two-way trade between the two countries does not amount to much: Myanmar last year was the United States' 84th biggest partner in the trade of goods such as automobiles and machinery.
US goods exports to Myanmar came to just $US338 million ($A443m); imports to $US1 billion ($A1.3b).