The move comes after days of Trump and other administration officials patently insisting that they had no actual policy of separating children from their parents-and had no authority to stop it.
"There will not be a grandfathering of existing cases", Kenneth Wolfe, spokesman for the Administration for Children and Families, part of HHS, told The Times.
Hastings said the policy isn't new, but officials had not previously acknowledged any flexibility under President Donald Trump's procedure for handling immigrant families, called "zero tolerance".
The administration has faced backlash this week for its zero-tolerance policy of separating migrant families illegally crossing the border.
The act does not mandate family separations.
House Speaker Paul Ryan told reporters that compromise legislation under discussion would provide funding to allow the Department of Homeland Security enough resources to house and care for families as they stayed together during the process. 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.
And of course, the obligatory "witch hunt" tweet: "I can't think of something more concerning than a law enforcement officer suggesting that their going to use their powers to affect an election!"
Katharina Obser, a senior policy adviser at the Women's Refugee Commission, said the order could result in expanded detention for immigrant families.
"Very important. We're going to be signing an executive order".
Although it was unclear if this is what Mr Trump is signing, he said he would be "signing something" and said he wants to keep families together.
"Congress and the courts created this problem, and Congress alone can fix it", Nielsen said Monday. Other recent rulings, upheld on appeal, affirm the children's rights to a bond hearing and require better conditions at the Border Patrol's short-term holding facilities. "And children shouldn't be punished for their parents breaking the law".