It looked like a happy holiday reunion: A 4-year-old boy wearing a Spider-Man baseball shirt sprinted across an airport baggage claim area in Austin, Texas, late Tuesday night and flung himself into his father’s arms, then immediately pulled toys out of his bag as if trying to catch his father up on all that was new in his life.

He had a Woody doll from “Toy Story,” a coloring book and stickers. There were a lot more toys in his suitcase, the boy squealed, between hugs and kisses. And, he announced, his eyes widening at the sight of a couple of fake reindeer displayed on baggage carousel 1, he’d seen reindeer for real. “Some of them have horns,” the boy giggled, poking his index fingers from each side of his head.

This reunion wasn’t about the holidays, however. It was the bittersweet homecoming of a father and son from El Salvador who’d been separated for more than 11 weeks and 1,800 miles for reasons the United States government still has not made entirely clear. Brayan and his father, Julio, are among a small, new wave of family separations that immigration lawyers and advocates say signal an unofficial continuation of the Trump administration’s controversial zero-tolerance policy.

Brayan, with striking reddish-blond hair, and his 27-year-old father came to the U.S. seeking refuge from gang violence in September but were separated at a border detention facility in Texas. Brayan was sent to temporary foster care in New York, Julio to an immigration detention facility outside San Antonio. ProPublica is not using their last name because the family is worried that Julio’s wife and stepson could face gang threats in El Salvador.

When ProPublica asked about their case, a Customs and Border Protection spokesperson said the agency had separated them for Brayan’s safety, and had evidence that Julio was a gang member. But the agency did not provide that evidence to ProPublica or to an immigration court or explain what made Julio a danger to his son. So, two weeks ago, an immigration judge released Julio from detention on bond to pursue his asylum claim. And late Tuesday night, authorities returned Brayan to his dad in Austin, where Julio’s mother lives.

While waiting for his son to arrive at the airport, Julio, still bewildered, kept revisiting the anguish he and his son had suffered during their separation. “I still don’t understand why they did this to us,” he said. “I guess they can do whatever they want.”

But when Brayan glided down the escalator, Julio was all tears of joy. “He feels skinnier to me,” Julio gushed. “Isn’t he beautiful?”

A Department of Homeland Security spokeswoman would not say why the agency had reversed course and allowed Brayan to be reunited with Julio.

But Anthony Enriquez, director of the unaccompanied minors program at Catholic Charities, said the reunion proved there had likely never been any justification for the separation.

The government, he said, had not provided Catholic Charities with any evidence or arguments that Julio was unfit or otherwise unable to care for Brayan. The same, he said, was true for other recent separation cases he’s handled. “Because the children were ultimately released without any attempt to justify the separation, there probably was no justification.”

That senselessness, he said, cast a pall over Julio and Brayan’s reunion. “As happy as these endings may be,” Enriquez said, “it’s hard to celebrate when we don’t know why they were separated and what the magic words were that got this reunification done.”

As ProPublica reported last month, nearly six months after a court ordered the government to end its zero-tolerance policy and stop separating immigrant children from their parents at the border, the government continues to do so. Authorities have been justifying the new separations by deeming the parents unfit, often due to vague and unsubstantiated criminal accusations. The separations are being conducted by Border Patrol officers in secret, without oversight by courts and child welfare agencies.

Once separated, advocates and social workers say, the children are arriving at shelters or foster care facilities without any notice that they came to the U.S. with their parents. Meanwhile, they say, no records are being kept ensuring children are not lost to their parents for unnecessarily long periods of time.

DHS sent Brayan to New York without indicating that he’d been separated from his father, and that his father was being detained in Texas. Authorities did not explain to Julio why they took away his son. A lawyer at Catholic Charities, which represents children at the foster care agency that provided a temporary home for Brayan, learned of the separation from ProPublica. That’s also how Julio’s lawyer learned about the government’s allegations against him.

“Every state and county in the country would prohibit the separations we are seeing at the border,” said Lee Gelernt, an attorney who led the ACLU’s lawsuit against the zero-tolerance policy. “But the government apparently believes that — in the immigration context — it is free from all the rules and counts on its actions at the border never coming to light.”

The ACLU’s suit resulted in an injunction, ordering the administration to stop separating children except in cases where a child’s safety was at risk. The government, Gelernt said, appears to be misusing that exception.

“We would have expected the government to cease all separations except where there was hard evidence that a parent genuinely poses a risk to a child,” he said. “But that does not appear to be the standard the government is using, in flagrant violation of the injunction.”

“The result,” he said, “is that little children are spending months all by themselves in government facilities wondering what happened to their parents.”

DHS spokeswoman Katie Waldman declined to comment, except to say that such separations are “rare.” She said there have been 81 cases since the administration retreated from its zero-tolerance policy. But she declined to provide a list of those cases, or the nationalities and ages of the children affected. She also declined to answer questions about how separation decisions are made; about why information about the separations is kept secret; about the agency’s allegations against Julio; or about whether separating Julio and Brayan was justified.

Julio’s lawyer, Georgia Evangelista, said she requested information from the agencies involved in the separation, and has gotten no response. She said she doubts the government has any evidence against Julio.

Tuesday night, under the bright lights of the airport, very little of that seemed to matter to Julio and Brayan. After scooping up his little boy, Julio made a video call to his wife in El Salvador, so that she could see Brayan for herself. As the two of them sniffled and wiped tears from their faces, Brayan seemed oblivious at first, still focused on showing his dad his new toys. Then he looked at the phone and saw his mom and started to cry, too.