"We still have to maintain toughness, or our country will be overrun by people, by crime, by all of the things that we don't stand for and we don't want", he said.
It was a dramatic turnaround for Trump, who has been insisting, wrongly, that his administration had no choice but to separate families apprehended at the border because of federal law and a court decision. GOP leaders are backing that option though it also lacks support it needs as of Wednesday morning.
Secretary of Defense Jim Mattis says the Pentagon will "respond if requested" to house migrants detained after crossing the U.S. -Mexico border illegally.
The order says the Department of Homeland Security - and not the Justice and Health and Human Services Departments, as under previous policy - would have continuing responsibility for the families. In the meantime, he said, this is not a matter for the Pentagon to comment on.
Katharina Obser, a senior policy adviser at the Women's Refugee Commission, said the order could result in expanded detention for immigrant families.
"We're going to have strong, very strong borders, but we're going to keep the families together", Trump said. The administration still has no real plans to address that financial and logistical problem before locking up immigrants, including asylum seekers.
"We can enforce our immigration laws without breaking families apart", said House Speaker Paul Ryan, R-Wisconsin.
"Of course we don't want families to be separated".
He made a rare trip to Capitol Hill late Tuesday to meet with GOP legislators and endorse a pair of bills that would keep detained families together, among other changes, but he remains confident that projecting toughness on immigration is the right call, said five White House officials and outside advisers who spoke on condition of anonymity because they were not authorized to speak publicly.
The proposed legislation, which includes additional immigration judges, has 27 Republican sponsors or co-sponsors, including Senate Majority Leader Mitch McConnell.
More than 2,300 minors were taken from their parents between early May and early June, according to statistics from the Department of Homeland Security.
Trump to be 'special guest' during House GOP Immigration Conference
A powerful conservative group, Heritage Action, also came out strongly against the bill -urging GOP lawmakers to vote no. One of them was a clean effort to give the dreamers a path to citizenship that was favored to pass if it got a vote.
On Wednesday, Trump said the "zero tolerance" policy would remain in place.
Almost all of the families, and many others, have officially requested asylum, citing the incessant violence in their home countries. Children are heard repeating calls for their parents. He said families would move to the head of the line for processing.
The order is titled "Affording Congress an Opportunity to Address Family Separation".
That lack of confidence and fear of retribution could make it significantly harder for Republicans to pass any politically risky immigration proposals ahead of the midterm elections in November. Ted Cruz, R-Texas, that would allow detained families to stay together in custody while expediting their hearings and possible deportation proceedings.
On Tuesday evening, protesters heckled USA homeland security chief Kirstjen Nielsen as she dined at a Mexican restaurant in Washington. Thus, the first images of such migrants in the USA media were exclusively of prepubescent and teenage males; which is to say, the kind of children that the right is most adept at demonizing.
- It's unclear what will happen to children already housed in shelters.
Under the bill, children under age 18 would be kept with their families in residential centers during legal proceedings.
De Blasio said he was unaware the children were being housed in the city, because it was not disclosed by the federal government.
DONALD Trump has fired back after an outpouring of emotion over family separations at the United States border that has seen his government repeatedly compared to the Nazis.
There is no law that would require the separation of families who try to cross the border illegally.