WASHINGTON — CUBANS on fragile rafts, Haitians on leaky boats, Chinese in rusty freighters: Illegal immigrants are descending on the United States from all directions. Where will it stop?
''This is just the tip of the iceberg,'' says Dan Stein, executive director of the Federation for American Immigration Reform.
Looking toward the Caribbean, Mr. Stein says: ''There is great pent-up demand to move to Florida. Not only in Cuba, but in Haiti, in the Dominican Republican, Jamaica, most of the Caribbean countries. And this pressure will continue to grow.''
The increasing numbers knocking on America's golden door are creating what Stein and a number of other analysts consider one of the greatest foreign-policy challenges of the next 20 to 30 years.
As world population soars, ethnic rivalries increase, and the competition for scarce resources -- especially food -- intensifies, the appeal of the US standard of living will be irresistible to growing millions in the third world. Europe, particularly Germany, is experiencing similar pressure.
As Haitians and Cubans have shown, many immigrants will do almost anything, pay any price, take virtually any risk, to reach the US. And the numbers seeking US refuge are certain to grow.
Within the next 35 years, the population of Mexico, the No. 1 source of illegal migration to the US, is projected to rise by 57 percent, according to the World Bank. Haitian and Cuban populations will each grow by 55 percent, Hondurans by 100 percent, Chinese by 25 percent, and Indians by 53 percent.
Not all immigration experts are as pessimistic as Stein. Jack Martin, an analyst with the Center for Immigration Studies, notes that illegal migration from Central America has abated since civil strife there decreased. Cuba and Haiti also may be special cases where migration pressure could ease once dictators are replaced, Mr. Martin says. But China may be a more serious problem, especially with its population expected to climb to 1.5 billion by 2030, he says.
Martin cites a 2-1/2-year federal study by Ko-lin Chin, a sociologist at Rutgers University in New Jersey, on the smuggling of Chinese from the Fuzhou region into the US. Approximately 10,000 Chinese from Fuzhou, guided by smugglers, arrive illegally in the US each year. Even when captured, illegal Chinese aliens are generally paroled into the community by immigration officials after only a day or so of detention. Deterrence is minimal.
Professor Chin worries that the growing underground community of these illegal immigrants is exacerbating America's crime problem. In a report, he said:
''Because of their illegal status, [undocumented immigrants] are going to be more daring and more violent when they are involved in criminal activities. In New York City, in San Francisco, and in Los Angeles, there's a lot of smuggling-related violence.''
Despite frequent warnings from experts on immigration, successive presidents -- Ronald Reagan, George Bush, Bill Clinton -- have failed to develop comprehensive policies to deal with the unlawful movement of people, critics say.
Demetrios Papademetriou, director of the immigration-policy program at the Carnegie Endowment for International Peace, concedes that some aspects in what has become ''a world trade in migrants'' may be beyond America's abilities to control.
Smugglers, often paid handsome sums, move would-be immigrants to the US from as far away as China or as close-by as Mexico. They often operate in gangs, sometimes go through third countries, and are increasingly skilled at avoiding US border police.
Even so, Mr. Papademetriou says the White House ''should draw the line'' and insist that unless an illegal immigrant from China, for example, is a true refugee whose human rights have been violated, and unless that refugee can fully document his case, he should be expelled from the US and sent home.
Instead of sticking with clear-cut policies, the Clinton White House sends out mixed signals, Papademetriou says. This indecisiveness constantly fuels hopes among would-be migrants that they will be allowed to remain in the US once they get here.
Stein is especially critical of the Clinton policy of housing Cubans and Haitians indefinitely at US military bases while a solution is sought to the problem of illegals.
He points out that with rising global populations, hundreds of millions of people are moving into ''mega-cities'' like Cairo and Mexico City. Many have per capita incomes of only $300 to $400 a year.
These people see the US military providing illegal migrants with three square meals a day, universal health care, and a roof over their heads.
''That's going to be a preferable lifestyle to not knowing where your next meal is coming from,'' Stein warns, and millions of other migrants may see Clinton's policy as an invitation to attempt an illegal entry to the US.