Secretary of Homeland Security Kirstjen Nielsen denied that the cages used to hold undocumented immigrant children at border detention facilities are, in fact, cages, during an aggressive exchange in congressional testimony on Wednesday.

Nielsen, who was in her third hour of aggressive questioning on border security matters by Democrats on the House Committee on Homeland Security, repeatedly refused to answer Chairman Bennie Thompson (D-MS) on whether U.S. Customs and Border Protection was “still putting children in cages” at detention facilities on the U.S. southern border. Nielsen instead described the cages as “areas of the border facility that are carved out for the safety and protection” of children in USCBP detention.

“Sir, they’re not cages. We don’t use cages for children,” Nielsen said. “To my knowledge, CBP never put a child in cages.”

“I just want you to admit that the cages exist!” Thompson said incredulously. “I saw them and you did too—all you have to do is admit it. Don’t mislead the committee. Do not mislead the committee.”

Images of migrant children sleeping under space blankets within the chain-link cages, reminiscent of dog kennels, helped ignite global outrage over the Trump administration’s policy of separating undocumented immigrants from their children at the U.S. southern border in late spring of last year. Children housed in the facilities often slept on thin pads over concrete floors, with limited access to washrooms and sinks.

Nielsen’s assertions that the facilities used to detain children at the border—which are, for the record, cages—followed another exchange with a Democratic lawmaker, where the secretary refused to admit that the Trump administration’s family separation policy was enacted to deter undocumented immigrants from seeking entry into the United States, before appearing to admit exactly that.

“Did you initiate the separation of families for the express purpose of deterring families from coming to the United States?” asked Rep. Elissa Slotkin (D-MI).

“No, I did not,” said Nielsen, before adding that “the whole purpose of that was to increase consequences for those who choose to break the law… if there is no consequences, we do not see the instances of the crime decreasing. So what we did was we increased the number of prosecutions.”

The exchanges heated up what had been relatively sleepy interrogation of the secretary by the committee up to that point, wherein Nielsen continued to deny that the Trump administration’s family separation policy existed—a position that Nielsen has taken since that policy first came to light in late spring of last year.

“There’s so much misunderstanding” about the family separation policy, Nielsen said in response to an intense line of questioning from Rep. Lauren Underwood (D-IL), a former nurse, about the health effects of separation on children. “There is no policy of family separation.”

Instead, Nielsen said, the administration was simply following the law by increasing prosecutions of undocumented adults for misdemeanor offenses—most critically, illegal entry. Since children are not allowed to be imprisoned with their parents, Nielsen reasoned, the policy of family separation was forced upon Homeland Security, rather than orchestrated by it.

“Families need to be put together—children should never be put in this situation,” Nielsen said, adding that the onus was on the parents “to not separate their children” by seeking entry into the United States.

More than 2,700 children were separated from their families before President Donald Trump issued an order ending the policy . When pressed on Wednesday, Nielsen could not say how many remain separated.