Donald Trump’s incoming border tsar, Tom Homan, has said that the US government “can’t find” more than 300,000 migrant children – and that many have been lured into forced labour and sex trafficking.

President-elect Donald Trump and his political allies, including Vice-President-elect JD Vance, have repeatedly made similar claims.

Some experts have accused them of distorting statistics to suggest the children are “lost” and victims of crime, although there is agreement that aspects of the system need to be changed.

The incoming administration has made immigration enforcement a priority, promising to clamp down on the US-Mexico border and conduct mass deportations of undocumented immigrants.

Let’s take a look at the claims of missing migrant children.

In an interview with Fox News on 26 November – just before a visit to the US-Mexico border in Texas – Homan accused the Biden administration of “bragging” about how quickly children are released from custody, as well as “not properly vetting” adult sponsors in the US.

“Shame on them,” he said of the Biden administration. “They have over 300,000 children that they have released [to] unvetted sponsors that they can’t find.”

“Many are going to be in forced labour. Many forced sex trade,” Homan added. “We need to save these children.”

In his October debate against Minnesota Governor Tim Walz, JD Vance also said that the Department of Homeland Security “effectively lost” a total of 320,000 migrant children.

Concerns over the plight of migrant children were also starkly highlighted earlier this week when authorities in Texas shared an image of a two-year-old girl from El Salvador found at the border clutching a piece of paper with a phone number.

“Putting optics over safety has led to countless children in danger or unaccounted for,” Tennessee Republican representative Mark Green told the New York Post.

“This refusal to protect vulnerable alien children from abuse, exploitation, and human trafficking will be one of the defining failures of the Biden-Harris administration.”

According to immigration experts and attorneys, the claims largely stem from an August report from the Department of Homeland Security’s inspector general’s office, which found that 32,000 unaccompanied minors failed to show up for court dates at immigration courts from 2019-23.

The report noted that 291,000 migrant children received no court notices at all. It also called on the US Immigration and Customs Enforcement (Ice) to “take immediate action to ensure the safety” of unaccompanied migrant children in the US.

Migrant children “who do not appear for court are considered at higher risk for trafficking, exploitation, or forced labor”, the inspector general’s office reported.

But Aaron Reichlin-Melnick, policy director at the American Immigration Council, a migrant advocacy group, told the BBC the figures are indicative of a bureaucratic “paperwork issue” rather than “anything nefarious”.

“When you hear the phrase ‘missing’, you think that there is a child that someone is trying to find and can’t,” he said.

“That’s not the case here. The government has not made any effort to find these children.”

Many of the children, experts say, may well be at the addresses that are on file with the government, but were simply unable to make their court dates.

“That doesn’t mean something bad happened to them,” Mr Reichlin-Melnick said. “It means you missed a court hearing.”

Mr Reichlin-Melnick added that there are “valid concerns” about exploitation.

“We cannot, however, suggest that all 320,000 of those children are being labour trafficked,” he said.

Eric Ruark, an immigration researcher with NumbersUSA – which calls for tighter border controls – said that the children are difficult to track “because of some combination of apathy, incompetence and bureaucratic inefficiency”.

“Many, hopefully even most, are safe with caring sponsors,” he added. “But the Biden administration can’t actually say one way or the other, and apparently doesn’t care enough to find out.”

Unaccompanied minors detained at the US-Mexico border go through a complicated process that begins with detention and processing by Customs and Border Patrol, or CBP.

If the child is from a foreign country that is not Mexico or Canada, they are placed into removal proceedings and transferred to the US Department of Health and Human Services, or HHS.

HHS, through its Office of Refugee Resettlement office, cares for the children in a network of state-licensed providers.

The office also seeks to reunify children with family members in the US or with individual or organisational sponsors – who in turn are obligated to ensure they arrive at immigration court dates.

Homan and other Trump administration officials have so far not provided many details about how they plan to address the issues that plague the detention of undocumented minors.

Several immigration attorneys contacted by the BBC suggested that the administration is likely to make becoming a “sponsor” for undocumented children much more difficult, even if the sponsor is a member of their family.

In practice, this would mean that more undocumented children are kept in detention.

“They could do what the Obama administration did, and detain them,” said Alexander Cuic, an immigration attorney and professor at Case Western Reserve University.

The controversial “Remain in Mexico” programme could also be applied to children, forcing them to wait across the border for the outcome of immigration proceedings.

“I’m not sure even they know what they’re going to do with the kids,” Mr Cuic said of the Trump administration. “But there’s a border problem they’re trying to figure out first, and that’s the first concern before whether they’re going to be harsh to both children and adults.”

When the BBC asked the Trump transition team what plan they have for the undocumented migrant children, spokesman Taylor Rogers said only that “Democrats’ wide-open border policies” have led to the children going “missing”.

“President Trump and leaders in his administration will deliver on their promise to end the invasion at our southern border that puts innocent children in harm’s way,” she added.