The current crackdowns intensify what human rights groups have condemned as "a wave of repression" against political challengers that was unleashed three years ago when 75 dissidents and journalists were rounded up, accused of treason and sentenced to an average of 20 years in prison.
The only woman among those "Black Spring" political prisoners, 60-year-old economist Marta Beatriz Roque, was released last year on health grounds but has been hounded by Castro supporters since.
News reports said she was attacked and beaten by a pro-government crowd as she left her Havana home on Tuesday.
"They shout insults and pound on my door at all hours," Roque said in a recent telephone interview from Havana. The harassment shows the regime's "debility," she said, but it succeeds in intimidating Cubans too fearful of the state to condemn it.
Cuba scholars say the harsh measures reflect Castro's efforts to preserve his nation's political system and his legacy.
Castro probably sees that his successors might be inclined toward more economic and political opening, said Wayne Smith, a retired diplomat who headed the U.S. Interests Section in Havana during the Carter administration.
"I don't think it's going to re-energize people and turn people back to that form of socialism," he said of Castro's recent efforts. "That's been discredited elsewhere in the world, and it's not working very well there."
Julia Sweig, Latin American studies director at the Council on Foreign Relations and author of "Inside the Cuban Revolution," traces Castro's intolerance of dissent to his conviction that the stability of the state requires "unity at all costs."
Cubans seldom share the zeal of the revolution's founders because the system provides residents with few of the opportunities that they are smart enough to envision and able-bodied enough to pursue, she noted.
"Young people coming out of the great health and education systems don't see they really have a future," she said. "And the older generations -- those who were part of the revolutionary ethos from the beginning -- they're dying."
Most Cubans' commitment to sharing and solidarity "went out the window in the '90s," said Philip Peters, Cuba analyst for the Lexington Institute think tank in Arlington, Va., recalling the Cuban leadership's replacement of moral incentives with material rewards to boost production in the lean years after Soviet aid stopped.
