"They really would like to have open borders where they can just flow in", Mr. Trump said of congressional Democrats.
The order specifies that migrants entering the United States with children will not be kept together if there's a fear for the child's welfare.
But the directive may violate a 2008 law that require special handling of migrant children who must be transferred from Nielsen's department to the Department of Health and Human Services after 72 hours.
President Donald Trump's immigration executive order attempts to solve one contentious action - the separation of families - but will bring back another - locking them up together indefinitely. That's just what he did.
'Get it done, always keeping in mind that we must have strong border security'.
Trump's order is likely to create a fresh set of problems involving length of detention of families, and may spark a fresh court fight. It's unclear what happens if no changes to law or the settlement take place by the time families reach the detainment deadline. "So I'm going to be signing an executive order in a little while before I go to Minnesota".
But the president says it is necessary to stop illegal border crossings. The government says that only happens when immigrants can not prove family relationship or when there is evidence children have been abused.More news: Amazon leaked Prime Day 2018 details
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Trump's family apparently played a role in his turnaround.
Several Republican members of the US House of Representatives who were briefed by Nielsen about Trump's executive order said they did not know if it would prevent family separations during detentions longer than 20 days.
Democrats welcomed Trump's apparent change of course but said he had only himself to blame. Assessments for possible detention facilities at military bases have already been done in Texas and another is expected in Arkansas on Thursday. The details of the executive order were worked out between the White House, the Justice Department and the Department of Homeland Security, a source said. Those people were not authorized to speak publicly and commented only on condition of anonymity. She was heckled at a restaurant Tuesday evening and has faced protesters at her home. Trump told House Republicans on Tuesday night he would support either of the immigration bills under consideration but did not give a preference. They want open borders, which breeds awful crime.
Following the meeting he tweeted: "Republicans want security".
Homeland Security Secretary Nielsen traveled to Capitol Hill Wednesday afternoon to brief lawmakers. If those options are exhausted, authorities must find the "least restrictive" setting for a child who arrived without parents.
The Anti-Defamation League, though, said the order is not a humane solution.
"When you prosecute the parents for coming in illegally - which should happen - you have to take the children away", he said. Most of the more than 10,000 children in shelters under HHS care came to the USA alone and are waiting to be placed with family members living in the U.S.
Now, questions were immediately raised about whether children will be released into foster or other care at the end of 20 days if their parents' immigration proceedings have not wrapped up.