White House officials have confirmed a plan to stop an exodus on the scale of the 1980 Mariel boat-lift, when Mr Castro allowed 125,000 Cubans to flee to Florida on boats, mostly supplied by Cuban exiles in Miami. 'You can be sure we would be ready to respond', one official said.
However, the State Department said there were no plans to return 26 alleged hijackers of a Cuban government boat to Cuba, saying there is no proof of Cuban claims that they killed a naval officer or committed other crimes in the incident on Monday. The refugees were picked up in the Florida straits on Tuesday.
The US authorities yesterday detained the 26 Cubans, pending investigation of the Cuban government's claims. 'We have not established that any capital crime was committed,' the State Department spokesman, Mike McCurry, said.
The alarm sounded at the end of last week, when Mr Castro blamed the United States for a series of recent hijackings of public ferries from the port of Havana and violent clashes in the capital last Friday between would-be emigres and the police.
Mr Castro then declared that his government would 'stop blocking the departure of those who want to leave the country'.
There is optimism, however, that Mr Castro may not carry out his threat. 'We believe, and have had external indications to this effect, that something similar to Mariel is not going to happen', an official told the Washington Post.
Contingency plans to deal with an exodus continue to be laid. Special presidential powers would be used mainly to prohibit Cuban Americans in southern Florida from setting out in private boats, as they did in 1980, towards their old country to pick up the new refugees. Violators would be fined and could have their vessels impounded. In 1980 Mr Castro actively encouraged American exiles to sail to Mariel, a port west of Havana, to pick up those fleeing the country. The operation, lasting several months, was dubbed the 'freedom flotilla'. The influx of Cubans into the US swamped the social services in southern Florida and may have contributed to the election defeat that year of Jimmy Carter. The state, which four years earlier had gone Democrat, voted heavily for Ronald Reagan.
Florida is testing its own emergency procedures for dealing with a refugee wave. A large part of the police force could be deployed to capture those coming ashore, to ensure that proper immigration processing is carried out. If the efforts to head off a new influx fail, a second plan, called 'Operation Distant Shore', has also been drawn up to deal with the immigrants, once they are in America. The first phase will be to dispatch the Cubans to army camps for processing. From there they will be settled in different locations around the US and not concentrated in one area, like Florida.
To some Cuban Americans, recent events are a sign that the Castro regime may be in its death throes. 'This is the beginning of the end', Rafael Penalver, a Cuban exile attorney in Miami said. 'Castro's government is collapsing. He's in free-fall right now'.
Even before Mr Castro made his threat, the flow of refugees from Cuba was speeding up. This year 5,163 Cubans have arrived in the US on boats or rafts, which is the largest number since Mariel.