After voicing support for Cuban anti-government protesters, the U.S. government on Thursday imposed sanctions on senior Cuban officials the White House blames for human rights abuses.
The move marked the first concrete steps by President Joe Biden to pressure Cuba's Communist government.
Thousands of Cubans staged protests a week ago to demonstrate against an economic crisis that has brought shortages of basic goods and power outages.
Hundreds of activists were detained.
Among them were actor and playwright Yunior Garcia, who spoke to Reuters this week while under house arrest.
"My current situation is that I have four officers in front of my door who prevent me from going outside. They told me I cannot even go to work. When I leave to buy cigarettes or food, one of them goes with me to keep me under vigilance. We know there are more, because we counted eight this morning."
Juan Papier monitors Cuba for the non-profit Human Rights Watch.
"We have conducted dozens of interviews to document the Cuban repression against protesters in Cuba. We have concluded that the repression has been brutal. Over 500 people including protesters, artists, journalists and others have been detained. The vast majority of them are being held incommunicated. The whereabouts of many of them are unknown. Many have been beaten, some have been tortured. And many of them are being subject to arbitrary criminal prosecutions based on Cuban legislation that guarantees no due process rights and no rights to defence."
The U.S. Treasury Department said that the sanctions had been placed on the minister of the Revolutionary armed forces and on an interior ministry security unit Washington blames for the crackdown.
The Cuban government has blamed the protests mostly on what it calls U.S.-financed "counter-revolutionaries" exploiting economic hardship.
U.S. officials have acknowledged that the targeted sanctions may not have much impact. Cubans rarely have U.S. financial dealings and seldom travel to the United States, limiting the practical impact of such measures.