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 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.

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.