Prior to Trump's remarks, White House aides refused to comment on rumors of an executive order and Republicans on Capitol Hill seemingly had no knowledge of a coming executive action.
But there is no law requiring children to be separated from their parents at the border, and Trump, whose administration imposed the rule, could have stopped the practice at any time without an executive order.
As CBS2's Alice Gainer reported, the order allows families to be held in detention together but does not reverse the administration's "zero tolerance" policy.
It's unclear how long it will take for Trump's order to be implemented.
The order directs other agencies, including the Pentagon, to take steps to find places to house family units. This decision was in a case that established standards for the care of migrant children - what is known as the Flores settlement. Children would be separated from adults who are not their parent or who have serious criminal records, or if there is evidence of abuse or trafficking.
Senate Majority Leader Mitch McConnell (R-Ky.) said Republicans need to fix the problem through legislation, and that the fix should be narrowly tailored.
"There are now 239 children right here as a result of the Trump administration's family separation policy", he said.
Democrats, however, indicated they were not satisfied with the action.
The Anti-Defamation League, though, said the order is not a humane solution. Pete Aguilar, D-Calif., told McClatchy. "We have no desire to be associated with separating families, or worse, to profit from it", the company said in a statement.
He did not immediately provide details of the bill, but said that it resolves the issue of so-called Dreamers, undocumented adult migrants who entered the USA as children, "in a very elegant way".
Ryan declined to say whether the president would commit to an immediate moratorium on family separation, but hinted that the administration is exploring "interim measures".
"I'll be signing something in a little while that's going to do that", Trump said.
The House of Representatives is expected to vote on two bills created to end family separations formally and deal with other immigration issues. "Obviously this is not the way we do things in Canada". The new Trump policy, unveiled Wednesday, involves keeping families detained together for an indefinite amount of time - a time that could stretch into months or even years if that family is seeking asylum. Obama wrote. "Do we look away, or do we choose to see something of ourselves and our children?"
In 2016, the 9th U.S. Circuit Court of Appeals ruled that child migrants who came to the border with parents and were held in custody must be released.
Republican leaders in the House are trying to put together an immigration bill that would keep immigrant children in detention indefinitely, but housed with their parents. Bob Goodlatte, R-Va., to cut back on both legal and illegal immigration.
But he did not demand members vote for Speaker Paul Ryan's more moderate immigration bill over a more conservative bill offered by Rep. Media reports have appeared about heart-rending scenes of children crying for their parents.
"It's the Democrats fault, they won't give us the votes needed to pass good immigration legislation".
More than 2,000 minors have been separated from their families since early May. Lamar Alexander of Tennessee, co-signed a letter to the Justice Department Tuesday asking the administration to pause the separation policy until Congress can address the issue.
But Republicans said they were uncertain if either measure would have enough support to be approved. Mexican families, although smaller in numbers, are usually immediately deported because their country is so close to the U.S. She says "please, please let our children go to their families".