The United States is to start vetting would-be refugees from Central America in their home countries instead of on American soil, and offer those in imminent danger a temporary haven in Costa Rica, officials said on Tuesday.
The announcement - a significant change in US immigration handling - comes after America toughened its southern border against a persistent flow of thousands of Central Americans fleeing violence, and as it steps up deportations of migrants who failed to win asylum.
It also arrives in a US election year in which migration is a hot-button issue.
Under the plan, to be carried out in coordination with the UN refugee agency UNHCR and the International Organization for Migration, "the United States government will pre-screen vulnerable applicants from the region seeking protection", the White House said in a statement.
It will focus on citizens of the so-called "Northern Triangle" in Central America comprising Guatemala, El Salvador and Honduras, which are prey to frightening levels of gang-related violence, poverty and corruption.
A White House spokesman, Eric Schulz, told reporters the initiative was to "promote safe migration", especially for the many children attempting the "harrowing and sometimes deadly trip" overland to the United States.
The White House statement added that asylum-seekers "most in need of immediate protection" would be transferred to Costa Rica.
There, they would be processed further before going on to the United States or another safe country.
UNHCR's representative for Central America, Carlos Maldonado, told a news conference in Costa Rica that "these people will stay a maximum of six months in Costa Rica with a humanitarian visa and will later leave for a third country".
During their waiting period, the applicants would receive English language and other courses to help them adapt to their new countries, he said.
Officers from the US department of homeland security will carry out the vetting in Central America, officials said.
Amy Pope, the Homeland Security deputy adviser on the National Security Council headed by President Barack Obama, told reporters that US procedures to date had proven "insufficient to address the number of people who may have legitimate refugee claims".
She called the deal to use Costa Rica as a safe stopover for refugees was "an extraordinarily important step forward for this program".
Officials stressed that Central American migrants entering Costa Rica without being processed in their home country first would not be included in the program.
Pope said the vetting to be carried out would be the same as that for all refugee applicants, describing it as "the most comprehensive screening we do for any category of immigrants coming to the United States".
US officials said they were additionally expanding an initiative for Central American minors, under which a migrant already legally in the US can ask for refugee status for them.
The broadened approach will now also permit adult children to be included, as well family members who are parents or caregivers.
The changes reflect efforts by Obama's administration to find a more effective solution to the wave of Central American migrants trying to enter the US.
In 2014, America saw a big spike in the number of unaccompanied minors crossing the border from Mexico.
The United States responded by having Mexico bolster efforts to stop those crossing the border, and by ordering the deportation of Central American migrants in the US whose application to stay had been rejected by courts.
At the same time, the United States has approved $750 million in aid to the Northern Triangle countries to boost security, in a bid to reduce the reasons so many people were fleeing.
Obama in 2014 issued a decree to allow migrants whose children are legally resident to apply for permits to live in America, which would have shielded millions from deportation.
But in June this year the US Supreme Court blocked that measure.
Hillary Clinton, who is campaigning to succeed Obama as President in a November election, said the ruling "could tear apart five million families facing deportation".
However Donald Trump, her Republican challenger, has taken a tough line on all immigration, and has vowed to build a wall along the US-Mexican border if he becomes president.