WASHINGTON — Acting Homeland Security Secretary Kevin McAleenan told members of Congress on Thursday that migrant children are only separated from their parents at the border under rare circumstances.

"This is in the interest of the child. This is carefully governed, it's overseen by a supervisor when those decisions are made," McAleenan said, noting fewer than 1,000 separations of parents from their children had occurred out of almost 400,000 border crossings by families since October 2018.

McAleenan was responding to a series of recent incidents described by Democratic members before and during his testimony in front of the House Oversight Committee. Members referenced incidents in which children were separated from parents who had minor violations, including a prior charge of marijuana possession or a woman who was arrested in a gang roundup after she had been abused by the gang.

McAleenan refused to respond to specific incidents. He said that the policy of separating children from their parents at the border now is identical to the one used prior to the "zero tolerance" policy in May and June of 2018, which systematically separated children from parents whose only crime was crossing the border illegally.

The House Oversight Committee recently released a report on family separations that indicated 18 toddlers were separated under zero tolerance. McAleenan said Thursday he had ordered Customs and Border Protection at the time not to separate any parents from children under five years old unless there were extenuating circumstances.

Separations of parents from young children were "likely due to another reason" beyond simply crossing the border illegally, he said.

McAleenan also addressed recent reports of overcrowding and poor conditions in Border Patrol stations where migrants are detained. He blamed Congress for not acting quickly enough to secure funding for extra space and for not allowing for increased capacity for adult migrants in Immigration and Customs Enforcement detention facilities when they did pass a funding bill last month.

Several Democrats asked McAleenan about Customs and Border Protection officers being part of Facebook groups that demean immigrants.

McAleenan said those officers are under investigation, but attacks on the Border Patrol are "unwarranted and damaging."