FORT LAUDERDALE, Fla. -

A last-minute disagreement delayed a planned guilty plea by an American who returned from Cuba decades after hijacking a jetliner to the communist island.

The attorney for 57-year-old William Potts objected to language in a proposed plea deal concerning the 13 years Potts spent in a Cuban prison for the crime. U.S. District Judge Robin Rosenbaum set another hearing for Thursday.

Potts is charged with kidnapping instead of air piracy, which carried a mandatory 20-year prison sentence. The new charge would give Rosenbaum flexibility to count the Cuban years toward his U.S. sentence. He could still get life.

The FBI says Potts claimed he had explosives when he hijacked a New York-to-Miami flight to Havana in 1984. He described himself then as a black militant and used the name "Lt. Spartacus."