As many as 25,000 Cubans living in the United States have outstanding deportation orders, according to Immigration and Customs Enforcement. They include people who pose a threat to national security or have serious criminal convictions and are considered priorities for immigration enforcement agents.

Despite being an enforcement priority, those immigrants haven't yet been sent back to Cuba because the government of President Raul Castro has not given them permission to return. It's unclear whether the Cuban government's position will change.

Sisi, a 50-year-old grandmother who moved to Miami with her family when she was 4, is one of those waiting and wondering what the future holds.

As a teenager in the 1980s, Sisi married a man involved in South Florida's booming cocaine trade. By the middle of the decade she'd become involved in the business herself and eventually served 2 ½ years in prison, cutting ties to her brief life of crime in 1989.

Though she served her debt to society for the drug conviction, what she didn't know at the time was that her criminal record would prompt immigration authorities to issue a deportation order in 2000.

"I was young, stupid. It's hurting me," said Sisi, who spoke to The Associated Press on the condition that she only be identified by her nickname because of her pending deportation order. "It's coming back now, a lot."

For decades deportation to Cuba has been complicated by the lack of diplomatic ties and the Cuban government's decision not to provide travel documents for most immigrants facing deportation.

A 1984 repatriation agreement includes a list of 2,746 people who had come to the U.S. in 1980 as part of the Mariel boatlift who should be deported. The mass migration from Cuba to Florida started when then-President Fidel Castro announced he would allow anyone who wanted to leave the Communist island nation. An estimated 125,000 Cubans made the perilous trip between April and October 1980.

ICE records show that 1,999 people on that list have been sent back to Cuba, including 1,093 since 2001. ICE is responsible for finding and removing immigrants living in the country illegally and those who have been ordered to leave.

More than 35,000 Cubans have outstanding deportation orders, and as of the end of March, more than 2,300 other Cubans have open cases pending in U.S. immigration court. ICE said of those, about 25,000 are considered deportation priorities because of their backgrounds, including criminal histories.

Sisi's lawyer, Grisel Ybarra, said the Cuban community is on edge amid the ongoing negotiations between Washington and Havana and the uncertainty about what renewed relations will mean for immigrants.

"Everybody in Miami right now is shaking like a leaf," Ybarra said. "People are really worried. The Americans and the Cubans are not in bed together, but they already have the room. It's happening."

Ybarra said she represents several clients who could face deportation, including Elias, a 71-year-old retiree whose deportation was ordered in 1991. Like Sisi, Elias agreed to speak about his immigration case only on the condition that his full name not published.

Elias said he has two drug-related convictions dating to the 1970s and 1980s. He moved to Florida in 1961, followed by other family members a decade later after his father spent about 10 years in a Cuban prison for being part of a union that opposed Communism. If he is forced to go back to Cuba, he said, he would be alone in a country he would barely recognize.

"I'm going to meet a new country," Elias said. "I've got nobody in Cuba. All my family is here. Anything that I love in this world is here."

Though the future of migration agreements between Washington and Havana have yet to be laid out publicly, under any circumstances the tens of thousands of Cubans with outstanding deportation orders aren't likely to be quickly sent home. That's because ICE already struggles to find and deport immigrants living in the United States.

During the first six months of the 2015 budget year that started in October, the agency has removed about 127,000 immigrants. If that pace holds, ICE will deport the fewest immigrants since the middle of President George W. Bush's second term in 2006.

If the Cuban government does begin accepting more deportable migrants, they would likely just be added to the ever-growing list of people who risk being expelled from the United States if ICE can find them, according the Migration Policy Center's Marc Rosenblum.

"There's definitely going to be a randomness to it," Rosenblum said.