President Biden faced more questions about immigration than any other topic during his first White House news conference Thursday, pledging conditions would soon improve for the record numbers of unaccompanied migrant teenagers and children held in U.S. custody.

In lengthy responses about care for the minors and the factors prompting their journey, Biden demonstrated the mix of sympathy, confusion and frustration that many in his new administration appear to share as they struggle with the logistical strains of the sudden influx and the delicate politics of immigration enforcement.

The president also conveyed his administration’s two-track enforcement message, describing the decision to welcome unaccompanied minors as a moral obligation while pledging to intensify the expulsion of family groups.

Biden largely blamed the Trump administration and seasonal factors for the precipitous increase in border crossings since his inauguration, even after ABC reporter Cecilia Vega said she spoke by phone to a Honduran mother who had sent her son alone to the southern border of the United States because she believed Biden would not deport him.

Biden said that his administration is not going to allow unaccompanied minors to “starve to death and stay on the other side” of the border,” but he was incredulous that a parent would choose to send a child based solely on the perception that he’s a “good guy.”

“It happens every single solitary year. There is a significant increase in the number of people coming to the border in the winter months of January, February, March,” he said. “The reason they're coming is that it's the time they can travel with the least likelihood of dying on the way because of the heat in the desert.”

While Biden is correct that the number of border crossings have typically increased during those months, the increase over the past eight weeks appears to be especially sharp, and Homeland Security Secretary Alejandro Mayorkas said earlier this month that the United States is “on pace to encounter more individuals on the southwest border than we have in the last 20 years.”

This month the number of unaccompanied teens and children taken into custody is on pace to exceed 17,000, a record, and overall arrests and detentions by U.S. Customs and Border Protection are projected to surpass 150,000 for March, preliminary figures show.

Nearly 12,000 teens and children are living in shelters run by the Department of Health and Human Services as they await placement with a vetted parent, relative or sponsor, the latest figures show. There’s not enough room in those shelters, and an additional 5,000 young migrants are waiting in Border Patrol facilities not intended for children.

Biden was asked when he would allow reporters to visit the overcrowded Border Patrol detention facilities where minors are being held far longer than the legal limit, in conditions that his administration has recognized as inappropriate. The president did not commit to a timeline for media access, but he said conditions were “already getting better.”

 “They're going to get a whole hell of a lot better real quick or we are going to hear of some people leaving,” the president said, the first time he has indicated that officials could be fired for their handling of the crisis.

“We're going to get it done,” Biden added, confirming he has turned to Pentagon officials for help, and they agreed to shelter up to 5,000 teens and children at Fort Bliss, an Army post in El Paso. “We’re going to significantly ramp up.”

Biden blamed former president Donald Trump for the acute overcrowding in recent weeks, saying his predecessor cut shelter capacity, requiring the new administration to “rebuild the system on the fly.” This week Biden administration officials told reporters the transition team asked the Trump administration to boost the number of shelter beds but it was slow to do so, leaving the incoming team with a deficit at the outset.

HHS records show the number of shelter beds topped 16,000 under Trump, an all-time high, but were reduced to about 13,000 in 2019.

Pandemic distancing protocols further reduced capacity last year, even as the number of minors crossing the border alone rose during the final months of Trump’s presidency, especially following a court ruling that blocked the government from sending minors home under the Title 42 public health order.

A 2008 law designed to protect trafficking victims generally prevents the swift return of teenagers and children who are not from Mexico or Canada, but the Trump administration effectively suspended those protections last year during the pandemic. In late January, an appeals court ruled that the return of the minors was legal, but the Biden administration announced it would not send the teens and children home and would allow them to pursue humanitarian claims under the law.

Biden accused the Trump administration of allowing migrant children to sit “on the other side of the Rio Grande by themselves with no help,” repeating some of the same mischaracterizations of the Title 42 process that others in his administration have made in recent weeks.

After the implementation of Title 42 last year, U.S. immigration officials generally used repatriation flights to send minors back to their home countries, as the Mexican government would not allow non-Mexican minors to return.

Biden also said incorrectly that “the vast majority of the families” are being sent home by his administration. The most recent data show that fewer than 20 percent are turned back to Mexico by the Title 42 policy, with the remainder generally released into the U.S. interior with a notice to appear in court.

Biden said his administration was in negotiations with Mexico to expand the country’s capacity to accept families returned by the United States.

“I think we’re going to see that change,” Biden said. “They should all be going back. All be going back.”

That prompted a retort from one of the lead immigration attorneys at the American Civil Liberties Union, which agreed this week to stall a lawsuit seeking to stop the expulsion of migrant families until April 2.

“We put our Title 42 case for families on temporary hold in exchange for good faith promise to negotiate,” the ACLU’s Lee Gelernt tweeted. “But POTUS JUST said his hope is that U.S. wants to expel ALL families if Mexico will allow them. Then litigation may be only choice.”

In interviews with migrant families along the border, as well as with parents discussing their decision to send a child alone, several Central American parents have cited Biden’s more welcoming image as a factor in their decision. Biden’s team has implored migrant families not to attempt the dangerous journey to the United States, but his administration made a flurry of early immigration policy changes that limited deportations, suspended border wall construction and terminated controversial Trump programs and policies that curbed asylum access.

I make no apologies,” Biden said, referring to the decision to end those programs. “I make no apologies for ending programs that did not exist before Trump became president, that had an incredibly negative impact on the law, on international law, as well as on human dignity.”

Despite Trump’s harsh rhetoric and policies, his administration faced a historic influx of Central American families in fiscal 2019, when border agents made nearly 1 million arrests. Trump turned to Mexico to boost its enforcement and allow for the expansion of the Remain in Mexico program, requiring asylum seekers to wait outside U.S. territory while their humanitarian claims were processed.

Many were stranded in Mexican camps for months with no response from U.S. authorities, in conditions Biden described as “sitting on the edge of the Rio Grande in a muddy circumstance with not enough to eat.” His administration allowed those asylum seekers to enter the United States while seeking protection.

Biden empathized with Central American families who are so desperate that they decide to make a dangerous journey to the United States, just as his own family did many years earlier.

“People don't want to leave,” he said. “When my great-grandfather got in a coffin ship in the Irish Sea, expectation was: Was he going to live long enough on that ship to get to the United States of America? But they left because of what the Brits had been doing. They were in real, real trouble. They didn’t want to leave, but they had no choice.”

“I can’t guarantee we're going to solve everything, but I can guarantee we can make everything better,” the president continued. “We can change the lives of so many people.”

Maria Sacchetti contributed to this report.