One riot doesn’t make a revolution. And this one was tame by U.S. standards: although dozens of people were hurt and scores of plate-glass windows were broken, there were no fatalities officially reported. But it was by far the most violent protest in Cuba in the 35 years since Fidel Castro took power. Witnesses said onlookers hurled bottles down on police from their apartments, shouting, “We’re starving”; the police seized videotapes from astonished tourists to use as evidence in court. “This is a pivotal event,” said a State Department official. It riveted Miami’s Little Havana and provoked a round of strategy sessions in Washington. With Haiti still simmering, the last thing President Clinton needed was another backyard test of his foreign-policy resolve. The riot also sent Castro into a paroxysm of spin control, built around the threat to allow another mass exodus like the 1980 Mariel boatlift that brought 125,000 Cubans to Florida. On Saturday, a week after the riot, authorities scheduled a huge rock concert on the Malecon, purportedly to help celebrate “The Year of Youth” – and Castro’s 68th birthday. But the extravagant gestures only underscored the question: how long can he hang on?

Deepening desperation has already created a slow-motion Mariel II. So far this year, nearly 5,400 Cuban boat people have reached Florida – more than in any other year since 1980. Uncounted others have died trying; one room in a Key West transit center is covered with slips of paper bearing the names of those who didn’t make it. And the exodus is expanding. The upsurge intensified last month, when a stolen tugboat with 72 refugees aboard collided with a Cuban chase craft; 41 people drowned. Havana’s archbishop issued a rare public protest – and the Cuban Coast Guard stopped chasing other escape vessels once they’re underway. Since then, Cubans have taken over three ferries and a single-engine crop-duster, creating an atmosphere of lawlessness. The riot began after a hijacking in which a 19-year-old policeman was killed. “I see a boat leaving now,” dissident writer Norberto Fuentes, himself on a hunger strike to force the government to let him leave, said in a telephone interview from his seafront apartment. “It’s a fishing boat jammed with people bailing with a bucket.”

On a televised tour of the riot scene, Castro looked stunned. And when Cubans heard he would address the nation, many hoped he would try to cool the tension by announcing more economic liberalization. Instead, he attacked U.S. immigration policy. Relatively few Cubans can get visas to visit the United States, but a 1966 law virtually guarantees a green card to any Cuban who can reach the mainland. This, Castro charged, lures Cubans into boats and endangers Cuban sailors and aviators; no Cuban refugee has ever been convicted of hijacking under federal law. But while Cubans are waved into Florida, Washington has shut down the Haitian boat people by warehousing more than 15,000 people on the U.S. Navy base at Guantanamo Bay. Castro called that a “concentration camp: brutal, uncivilized, savage.” “If the situation remains the same, we will not take action against any boat that comes to look for people in Cuba or against boats that leave from Cuba with people,” he said.

Within hours, U.S. officials were leaking contingency plans for Operation Distant Shore, a two-way naval blockade. The coast guard would block Miami-based Cubans from embarking to pick up relatives and would intercept Cuban boat people at sea and ship them to military installations outside Florida. Leaders of Cuban exile groups quickly fell into line, arguing that Cuban dissidents will do Castro much more damage at home. “If they start coming here and they stay here, we’re never going to liberate Cuba,” says Arturo Cobo, director of the Key West shelter. “The solution to emigration pressures from Cuba is rapid, fundamental and far-reaching political and economic reform,” said Attorney General Janet Reno, a former Floridian herself. Still, Castro evidently scored with his barbs about a free ride for hijackers under U.S. justice. In Key Largo, police picked up three men after they allegedly unloaded 22 Cubans at a resort, and immigration officials detained the crewman of a hijacked trawler, accused by Castro of murdering an officer on board the ship.

Castro’s latest maneuvers only revealed a weak hand. At the same time he was blustering about opening the floodgates, he reportedly assured U.S. officials he would not set off another mass wave of emigration. He can’t afford to. “In 1980, 125,000 left,” said a Havana man. “Today there woud be millions who would go, and Fidel knows that.” But if he doesn’t let Cubans out he may soon have to shoot them down, an issue that divides the ruling party. And his effort to ease the effects of the U.S. embargo by promoting tourism and letting U.S.-based exiles send in dollars seems only to have created a new underclass, burning with resentment. “All I know every day is that my family does not have dollars,” says Junior, as plainclothes detectives loiter conspicuously on the Malecon. “That’s the measure of our life.” It’s doubtful that Castro has heard the last from Junior and his friends.