As the first year of President Donald Trump’s zero-tolerance border policy comes to a close, the Biden administration’s effort to reunite separated children and parents is making headway.

The Department of Homeland Security planned to announce on Thursday that 100 children, mostly from Central America, have been reunited with their families, and that approximately 350 more reunifications are in the works after it adopted measures to improve the program.

“I would have preferred that this happened much sooner. But we’re making headway, and I think we’re gaining traction,” said Michelle Brané, executive director of the administration’s Family Reunification Task Force.

On his first day in office, President Joe Biden issued an executive order to reunite families who had been separated as a result of the Trump administration’s widely condemned practice of forcibly separating families and children at the US-Mexico border in order to discourage illegal immigration. The task force’s work has been hampered by a number of factors, including insufficient or missing records on separated families, the sheer volume of cases, and the fact that many parents are in remote Central American communities and have been unable to locate or return their children to the United States.

When the administration announced a partnership with the International Organization for Migration and the creation of a web portal — or — for parents to contact the US government and work through the reunification process in September, the task force had reunited 50 families.

Under Trump, approximately 5,500 children were forcibly removed from their parents, mostly in 2018, as his administration sought to deter an increase in people crossing the U.S.-Mexico border through criminal prosecutions, even if the migrants were presenting themselves to authorities to seek asylum as permitted under the law.

Trump ended the practice in June 2018, just days before a judge ordered an end to the program in response to a lawsuit filed by the American Civil Liberties Union, despite widespread condemnation, including from Republicans.

Brané stated in an interview prior to Thursday’s announcement that officials believe there are still approximately 1,150 children whose whereabouts are unknown. The total fluctuates as some cases are resolved with new information and new ones emerge, including those who contacted the new web portal.

“Obviously, this isn’t the end,” Brane said. “This is just the start of this ramp up, and hopefully families will see that reunifications are taking place and will feel confident in coming forward.”

Parents and children, including some who arrived at U.S. airports this week, are being granted humanitarian parole, which allows them to stay in the country for a minimum of three years and apply for permanent residency through asylum or another program. In addition, they are receiving counseling services.

Hundreds of families have also taken legal action against the federal government.

After eight months of talks, the Justice Department informed lawyers representing several groups’ families last week that it was withdrawing from settlement negotiations and would defend each case in court.

This came after media reports of a proposed settlement that would include payments of several hundred thousand dollars to each affected person infuriated Biden administration critics in Congress and elsewhere.