Janet Reno, the US Attorney General, would use force to return Elian Gonzalez to his father, news reports in the Washington Post said yesterday.
Ms Reno has played a prominent and controversial role in the saga of the six-year-old Cuban boy, who is the subject of a tussle between his Cuban father and his relatives in Miami.
The attorney general used to live in south Florida and held office there, and the Cuban-American population of Little Havana in Miami regards her as a traitor.
In a highly emotional meeting on Friday with Juan Miguel Gonzalez, the boy's father, Ms Reno promised to return the boy to him. "There is a bond, a special, wonderful sacred bond, between a father and his son, one I intend to uphold," said Ms Reno.
But there are still vivid memories in America of the deaths at Waco, Texas, when dozens died as federal officials stormed a cult headquarters, an event that led to the bomb in Oklahoma City.
If the Miami relatives refuse to turn over the boy to his father, US marshals and immigration officers would go to their home and take custody of the child, said the Post yesterday. They would go by daylight, because this would be less stressful for Elian than a night appearance.
Ms Reno and her deputy Eric Holder say they prefer a peaceful resolution after weeks of negotiations, but they are ready for the potentially ugly spectacle of televised conflict with protesters in Miami to uphold the law, said the paper.
A official said: "We fully expect the local police to fulfil their responsibility to the citizens of the city of Miami and Dade County to protect innocent people from being harmed and property from being destroyed."
The mayor of Miami-Dade County, Alex Penelas, had said local law officers would not assist the US government, though he has been forced to reiterate his position in much less confrontational terms.
A meeting tomorrow will bring together the Miami relatives with psychiatrists and psychologists to discuss how to manage the handover. On Tuesday, the US government is expected to transfer custody of the boy to his father and specify where and when he should be returned.
The father would be free to go back to Cuba with his son, said Ms Reno. By the end of next week, Elian could be home.
How the protesters in Little Havana will respond is a problem. Late on Friday, they postponed plans for a programme of civil disobedience, saying they would wait to see how the timetable emerged.
"We want to send a strong, civilised message of our concerns to the government," said Ramon Saul Sanchez of the Democracy Movement.
But tomorrow they could take action, and if the US marshals come for the boy, there may be violence.