The Office of Refugee Resettlement is preparing for the possibility of another surge in family separations. Internal documents obtained by Slate show that ORR has modeled a scenario in which the Trump administration’s border policies could require the detention of thousands more immigrant children.

The ORR ’s budgeting exercise is premised on the possibility it could need as many as 25,400 beds for immigrant minors by the end of the calendar year.

ORR—an agency within the Administration for Children and Families, which is itself a division of the Department of Health and Human Services—was caught off guard by the family separation policy, the documents reveal. In April, Attorney General Jeff Sessions announced that the Department of Justice would henceforth have “zero tolerance” for immigrants who cross the border without authorization. He expanded the policy in May by partnering with the Department of Homeland Security to prosecute immigrants for unlawful border crossing, a misdemeanor. Under zero tolerance, parents are imprisoned, and children are placed in ORR shelters, sometimes far from the border.

There are currently about 11,800 children in ORR’s care. Alex Azar, the secretary of the Department of Health and Human Services, has stated that somewhere between 2,000 and 3,000 of those children were separated from their parents at the border. The remaining children in ORR custody are unaccompanied minors—children who crossed the border without a parent or guardian.

In the documents obtained by Slate, ORR officials describe the budget implications of a potential surge in immigrant minors over the next three months. The ORR’s budgeting exercise is premised on the possibility that the agency could need as many as 25,400 beds for immigrant minors by the end of the calendar year. The documents do not indicate that ORR officials have specific knowledge that family separations will increase but do show that the agency is preparing for the possibility.

The internal documents estimate that if 25,400 beds are needed, ORR would face a budget shortfall of $585 million for ORR in fiscal year 2018, which ends on Sept. 30. Under this scenario, that shortfall would increase to $1.3 billion in the first quarter of fiscal year 2019, adding up to a total shortfall of $1.9 billion for the period between Oct. 1, 2017, and Dec. 31, 2018. The documents stress that these budget estimates represent maximum possible expenditures and that actual expenses may be lower. The Department of Health and Human Services did not respond to multiple requests for comment about these figures or anything else relating to the documents.

To help cover these potential costs, the documents say, HHS will seek supplemental appropriations from Congress. The documents also indicate that HHS plans to pay for child separation by reallocating money from the Ryan White HIV/AIDS Program, which, according to its website, “provides a comprehensive system of care that includes primary medical care and essential support services for people living with HIV who are uninsured or underinsured.” Per the documents, the process of transferring those HIV/AIDS funds has already begun.

In addition, HHS plans to reallocate $79 million from programs for refugee resettlement, a move that could imperil social services, medical assistance, and English language instructions for refugees in the U.S., as well as programs for torture survivors.

ORR’s budgeting exercise does not account for a federal court decision ordering the administration to reunify separated parents and children within 30 days, or within 14 days if those children are younger than 5 years old. Azar has stated publicly that he will attempt to comply with these deadlines.

The documents do, however, take into account the executive order that Trump signed on June 20 that purports to end family separation—and reveal that ORR does not seem to be operating on the assumption that the separation policy has truly ended. The budgeting exercise assumes that Trump’s order created a 20-day pause on family separations and that referrals would increase after that 20-day period—that is, after July 10—to 325 immigrant children per day for four weeks. If that estimate is correct, that means an additional 9,100 immigrant children would be detained and housed by the U.S. government in the four weeks beginning Tuesday.

At the end of those four weeks, the agency documents assume, the deterrent effect of family separation would again reduce referrals—that is, the number of immigrant children in government detention. There is no evidence that a resumption of family separation will deter parents from crossing the border with their children; the number of families apprehended at the border stayed flat between May and June as the U.S. government implemented the zero-tolerance policy.

The timeline laid out in these internal documents reflects a debatable reading of Trump’s executive order. ORR officials appear to think that the order allowed families and children to be detained together temporarily but that under the Flores settlement these children must be transferred to ORR’s custody after 20 days. Under this interpretation of the executive order, all children who are separated from a parent or guardian from this point forward must first be detained with that parent or guardian for 20 days.

While the executive order is ambiguous on this point, ORR’s interpretation is plausible. Moreover, not all of the referrals—ORR’s term for minors placed in its care—that are accounted for in ORR’s budgeting exercise would be children separated from their parents. Some of the additional beds would presumably go to minors who arrive at the border unaccompanied by a parent or guardian. But given the claim in the documents that referrals would increase after a pause on family separations, it appears ORR believes a substantial number of those beds would indeed go to children separated from their parents.

Mark Greenberg, a senior fellow at the Migration Policy Institute who led the Administration for Children and Families—the division of HHS that includes the Office of Refugee Resettlement—from 2013 to 2015, told Slate the plans indicate an “enormous increase” in the number of minors that will be held in custody. “This envisions having further family separation cases coming to HHS—a lot of them,” he said. Greenberg also noted that the documents suggest the possibility of a vast expansion of federal expenditures on unaccompanied minors. “The entire appropriation for unaccompanied alien children this year was $1.3 billion,” he said. Now ORR is “seeking an additional $1.3 billion” for just the last three months of 2018.

Bob Carey, who served as director of ORR under President Barack Obama, told Slate that the documents also reflect the possibility that the agency may “keep children for much longer periods of time.” Under Obama, the average minor in federal custody remained in ORR’s care for 33 days before being released to a sponsor, usually a family member. Under Trump, that average has increased to 55 days, and stints in detention could grow longer as the administration creates higher barriers to sponsorship. Carey said the Trump administration has implemented processes that have a “deterrent effect” on sponsors. For instance, ORR now shares information about potential sponsors with Immigration and Customs Enforcement. That policy could dissuade undocumented family members from sponsoring minors, potentially keeping children languishing in ORR’s care for months.

“That tactic represents muddying of mission,” Carey said. “ORR shelters were not established to care for children on a long-term basis. They were set to keep kids for as short a period of time as possible until the child could be released to a parent or other sponsor. Clearly [the agency] is creeping away from that.”