The Trump administration has still not reunited nearly 600 migrant children that it separated from parents at the border in recent months, according to a court filing on Thursday.

In a status report in a case involving a lawsuit brought by the American Civil Liberties Union on behalf of separated migrant parents, the governments lawyers said that more than 1,500 children had been reunited with their parents and about 400 more children were discharged from government custody through other circumstances, some to parents and others to sponsors.

However, the U.S. Justice Department lawyers reported that an additional 572 children remained in government-contracted shelters without their parents a full week after the court-ordered July 26 deadline to reunify separated families.

The government had not deemed those parents eligible for reunification because they had been deported, had been released into the interior of the country, had failed a background check or had yet to be located. The parents of more than 400 detained children, for instance, were no longer in the U.S. which a government official previously said was because they had been deported.

Earlier this week, U.S. District Judge Dana Sabraw in San Diego ordered the government to detail its plan for reuniting kids with parents who were deported or released.

In the Thursday court filings, the Trump administration said it was on the ACLU and their considerable resources and their network of law firms, NGOs, volunteers, and others to locate parents who had been deported or released.

The ACLU, in turn, said the onus was squarely on the government to find parents its officials had separated from their children at the U.S. border.

The Government must bear the ultimate burden of finding the parents, the ACLU said in the filing . Not only was it the governments unconstitutional separation practice that led to this crisis, but the United States Government has far more resources than any group of NGOs.

In June, Sabraw ordered the Trump administration to reunite the more than 2,500 migrant children officials had taken from parents as a result of Trumps hard-line zero tolerance policy on immigration.