Guillermo Fariñas, a veteran Cuban dissident known for long stints in prison and frequent hunger strikes, said he couldn’t believe his eyes as the police station he was briefly held in following mass protests on Sunday filled up with unfamiliar faces, many of them teenagers.
He didn’t recognize any of them from traditional opposition circles, he said.
“I told the state security guard who arrested me, ‘You’re going to have to change,’” Mr. Fariñas, 59, said. “‘This is the people, and not just the people, but the youth. Look at them: They’ve decided they are not just going to continue leaving the country — they want change here.’”
In the aftermath of a remarkable wave of demonstrations across Cuba over the weekend, the government detained dozens of people in a crackdown that activists described as the largest in years, perhaps even decades.
One longtime human rights activist said that the nationwide sweep of arrests was comparable only to the crackdown that preceded the 1961 invasion at the Bay of Pigs.
Amnesty International said on Tuesday that it had compiled a list of 150 people detained in the wake of Sunday’s demonstrations. Another group, the Movimiento San Isidro, a Cuban dissident group led by artists and academics, tallied 171 reports of people who were detained or who vanished in the wake of the protests.
“The massive peaceful protests were historic,” said Erika Guevara-Rosas, the Americas director at Amnesty International. “While the forms of repression are the same, we’re watching a substantial and dangerous mobilization of police and military security forces.”
Human rights groups said it may take several days to get a clear picture of the scale of the government response because spotty phone and internet connections have made it difficult to track how many people were taken into custody.
But Cubans reported seeing a strong presence of security forces on the streets on Monday and Tuesday, and many families were desperately trying to track down loved ones who were detained or who vanished after the demonstrations. The Cuban government said that one person was killed during a disturbance in Havana on Monday.
Still, veteran dissidents said the repression was to be expected following what many called the biggest day of protest in the country since the Cuban Revolution, forcing Cuba’s leaders to acknowledge the severe economic crisis that had sent thousands into the streets. Many described it as a potential turning point in a country where the Communist Party has managed to stifle even small challenges to its authority for decades.
“The spark has been lit, ladies and gentlemen, there’s no turning back,” the independent journalist Yoani Sánchez said in a brief podcast she recorded on Tuesday. “People felt what it’s like to scream freedom in the streets of Cuba.”
The Cuban government often detains dissidents for a day or two after security forces break up demonstrations. It was unclear whether Sunday’s detentions would lead to a new generation of long term political prisoners.
Daniel Triana, a Cuban actor who was held at a Havana detention center for about 24 hours, described a flood of protesters being led into the cell where he was kept.
“A lot of people throughout the country are still detained, I would say hundreds,” he said in a phone interview. “In my wing, there were dozens of people and they were bringing in people when I got there, and they were bringing in people when I left.”
Camila Remón, a member of Movimiento San Isidro, said the recent protests were enabled by widespread internet connectivity on the Island, a relatively new phenomenon.
“It’s been a very effective means to speak out,” she said, noting the flurry of online videos, many of them broadcast live, that gave people around the world a real-time glimpse of what was happening inside Cuba as the protests unfolded. “We’ve managed to get out a lot of content showing what the regime does.”
But internet service was soon shut down across the country on Sunday, and many activists have reported trouble connecting this week. Dissidents said the government appeared to be restricting access to a tool that poses a dire threat to its hold on power.
“The only thing that gave us the bravery to hit the streets was seeing that other people were also doing it,” said Mr. Triana, the artist. “Cutting the internet will squash all the security we had.”
In Florida, local leaders on Tuesday discussed ways to empower opposition groups in Cuba. Gov. Ron DeSantis expressed interest in having local companies explore the possibility of vastly expanding access to the internet on the Island.
Senior Cuban officials appeared shaken by the magnitude of Sunday’s protest, which unfolded in dozens of towns and cities across the island. Large defiant crowds of protesters denounced the state, the rising cost of living and worsening shortages of food and medicine.
President Miguel Díaz-Canel Bermúdez called on government supporters to take back the streets and invoked the prospect of violence as the government seeks to assert control.
“We will not surrender our sovereignty, the people’s independence, nor the freedom of this nation,” he said Sunday after the protests. “There are many among us revolutionaries who are willing to put our lives on the line.”
The following day, Rogelio Polanco Fuentes, the head of the Communist Party’s ideological department, said the protests were part of a form of “nonconventional warfare” the United States was waging in the pursuit of regime change.
“It involves tactics of so-called nonviolent struggle that generate instability and chaos in countries, to provoke the security forces into acts of repression,” he said. “These, in turn, generate the perception of human rights violations.”
But many leaders around the world, including President Biden, quickly embraced the protesters’ cause and condemned the wave of detentions.
“The place for these people is not in prison but in a public discourse,” Peter Stano, a spokesman for the European Union, told reporters on Tuesday. “We call on the Cuban authorities to release immediately all the people who have been detained based on their political conviction and based on their journalistic work.”
Activists on the island said that many people had been released, particularly well-known dissidents and people who had not committed any acts of vandalism.
Julie Chung, the top American diplomat for Latin America, said the detention and disappearance of protesters “remind us that Cubans pay dearly for freedom and dignity.”
With tensions running high on Tuesday, many independent journalists and activists reported being forbidden from leaving their homes. That was the case for Denis Solís, a musician who sings against the Cuban government, who had just been released from an 8-month prison term when Sunday’s protests broke out.
But thinking about what his fellow citizens had done, Mr. Solís was in a jubilant mood.
“I can’t believe what is happening,” he said. “It’s what we have been waiting for since 1959. Something that was impossible was made possible.”
Oscar Lopez contributed reporting.