Foreign parents are dumping their kids at the US border or into the hands of smugglers, and not wanting them back into their own custody. The Trump Administration has been soundly blamed for the children in US custody un-reunited with their parents but it’s not for lack of trying on the government’s part.
(From article) “DHS has taken every step to facilitate the reunification of these families where the parents wanted such reunification to occur. The simple fact is, after contact was made with the parents to reunite them with their children, many parents have refused. In the current litigation for example, out of the parents of 485 children whose plaintiff’s counsels have been able to contact, they have yet to identify a single family that wants their child reunited with them in their country.
“The result is the children remain in the U.S. while their parents remain in the home country.”