The Biden administration is threatening to sue Texas over Gov. Greg Abbott’s bid to yank the state-issued licenses of any shelter or facility that houses unaccompanied migrant children.

In a disaster declaration issued on Memorial Day, the Republican governor instructed officials to terminate the state licenses of shelter and foster care facilities that housed migrant children who are in the custody of the federal government. In the wake of that directive, officials instructed shelters caring for migrant children to end those operations by Aug. 30.

The move was a significant escalation of Texas’ fight against the Biden administration on immigration-related issues. It threatened to result in the closure of shelter facilities and disrupt the system that cares for and houses migrant children – potentially forcing the government to move the kids to facilities that are not designed to hold minors for extended periods of time.

The law requires migrant children who cross the border alone to be moved out of Customs and Border Protection facilities within three days and into the care of the Department of Health and Human Services’ Office of Refugee Resettlement, or ORR. The agency houses the children in state-licensed care facilities as local officials vet sponsors already in the U.S. to release the children to – a process that takes on average about a month, but can be longer.

Fifty-two such state-licensed shelters in Texas house thousands of migrant children.

HHS threatened to take legal action against the state if it did not stop its effort to pull the shelter licenses, HHS Deputy General Counsel Paul Rodriguex warned in a letter sent Monday night to Abbott, Texas Deputy Secretary of State Jose Esparza and Cecile Erwin Young, the commissioner of the Texas Health and Human Services Commission.

“ORR operates 52 state-licensed facilities in Texas, which comprise a significant portion of ORR’s total operational footprint, and represent an indispensable component of the Federal immigration system. If interpreted to reach ORR’s network of grantee-facilities in Texas, the May 31 Proclamation would be a direct attack on this system,” the letter says.

Rodriguez gave officials until Friday to clarify whether they intended to make an exception to the directive for shelters overseen by ORR.

Abbott’s order instructed officials to pull the licenses of facilities that care for migrant children in the U.S. unlawfully, and Rodriguez argued in his letter that the U.S. government does not consider children in ORR care to be unlawfully present under immigration law.