The United States imposed sanctions on Cuba's defense minister and a special forces unit Thursday for repressing peaceful protests, a step President Joe Biden warned is "just the beginning" of punitive measures against Havana.

The US Treasury Department said its Office of Foreign Assets Control froze the assets of minister Alvaro Lopez Miera and the Special National Brigade (SNB), a division of Cuba's interior ministry, in relation to human rights abuses committed during a crackdown on protests on the island earlier in July.

"This is just the beginning -- the United States will continue to sanction individuals responsible for oppression of the Cuban people," Biden said in a statement.

The sanctions were imposed under the Magnitsky act, which allows a US president to take action against human rights abuses and corruption.

Biden said his administration targeted Lopez Miera and the SNB -- a special forces unit nicknamed the Black Berets -- because they were "driving the crackdown" against protesters who took to the streets by the thousands in rare public demonstrations against the communist government.

"As we hold the Cuban regime accountable, our support for the Cuban people is unwavering," Biden said.

The United States sanctioned Cuban Defense Minister Alvaro Lopez Miera in relation to a crackdown on recent protests on the island
The United States sanctioned Cuban Defense Minister Alvaro Lopez Miera in relation to a crackdown on recent protests on the island AFP / Adalberto ROQUE

The president also condemned what he called "the mass detentions and sham trials" used to imprison and silence outspoken Cubans.

Cuba pushed back swiftly, calling the sanctions "slanderous" and saying the United States should focus more on repression and police brutality on its own soil.

"I reject unfounded and slanderous sanctions by the US government" against the Cubans targeted, Foreign Minister Bruno Rodriguez said on Twitter.

The sanctions freeze all Lopez Miera and SNB assets and interests in the United States, as well as prohibit any US citizen, resident or entity from engaging with them financially.

"Treasury will continue to enforce its Cuba-related sanctions, including those imposed today, to support the people of Cuba in their quest for democracy and relief from the Cuban regime," Treasury Secretary Janet Yellen said.

Biden, for his part, said Washington was considering multiple new steps.

The United States is working closely with regional partners like the Organization of American States "to pressure the regime to immediately release wrongfully detained political prisoners, restore internet access and allow the Cuban people to enjoy their fundamental rights," he said.

A woman speaks to the crowd during a protest showing support for Cubans demonstrating against their government, in Union City, New Jersey, on July 18, 2021
A woman speaks to the crowd during a protest showing support for Cubans demonstrating against their government, in Union City, New Jersey, on July 18, 2021 AFP / Kena Betancur

Washington is also reassessing its policy guiding remittances to Cuba, with the State Department expressing concern that such funds could "find their way into Cuban government coffers," according to spokesman Ned Price.

Washington will "continue to review what more we can do" to support the Cuban people while holding the nation's authorities to account, Price said.

On July 11 and 12, thousands of Cubans took to the streets in 40 cities shouting "Freedom," "Down with the dictatorship," and "We're hungry."

One person has died and more than 100 have been arrested since the protests broke out over the worst economic crisis in decades.

According to the Treasury Department, Cuba's defense ministry and security services attacked people and "arrested or disappeared over 100 protesters in an attempt to suppress these protests."

The demonstrations have further strained an already tense relationship between Washington and Havana.

Cuba has seen a whiplash in US policy in recent years, with former president Barack Obama normalizing relations at the end of his term, declaring that a half-century of efforts to topple the regime had failed, and then his successor Donald Trump reimposing sweeping economic pressure.

Biden as president had exhibited a go-slow approach to Cuba, but the unrest has thrust the relationship into a spotlight.

Several US lawmakers, including Democratic Senator Robert Menendez, the son of Cuban immigrants and chairman of the Senate Foreign Relations Committee, applauded the administration's sanctions.

For some Republicans it was not enough.

Senator Roger Wicker tweeted on Thursday he was "disappointed in the weak response from (Biden) and @StateDept as the Cuban people cry out for help."