Immigrant children: Here's what we still don't know after Trump's executive order

President Donald Trump's new executive order halts the separation of children from their families at the border.

But there are many questions that remain unanswered.

1. How will children who are already detained be reunited with their families?

The order does not explicitly address what happens to children who have already been separated from their families.

The fate of the more than 2,000 children who were separated from their families since the Trump administration started enforcing its zero tolerance policy remains unclear.

One official familiar with the scope of the president's order said that the directive only applied to new cases involving children arriving in the U.S., with illegal immigrant parents or guardians.

Brian Marriott, spokesman for the Department of Health and Human Services which is managing the detainees' care, said late Wednesday that the agency was "awaiting further guidance" on the reunification of children.

"It is still very early," Marriott said. "Our focus is on continuing to provide quality services and care to the minors...and reunifying minors with a relative or appropriate sponsor as we have done since HHS inherited the program."

2. Where will the families go?

The order will keep families who try to cross the U.S. border together in detainment. And it requires the Defense Department to house them, whether on military bases or, if necessary, newly constructed facilities.

But the administration has yet to spell out details.

Secretary of Defense James Mattis has largely deflected questions about what bases would be available and how the detentions would work, saying he was awaiting a request from the Department of Homeland Security.

"We'll see what they come in with. We support DHS and right now this is their lead and we'll respond if requested," he said Wednesday. "We have housed refugees. We have housed people thrown out of their homes by earthquakes and hurricanes. We do whatever is in the best interest of the country."

3. What does this mean for adults who are charged?

The zero tolerance requires prosecution of all adults caught crossing the border illegally. That is what has led to the thousands of family separations, and Trump has insisted that the policy will continue.

Marjorie Meyers, the chief federal public defender in southern Texas, said her office had received no information about how the order would play out. It's unclear whether the government plans to hold people in immigration detention and not hold them in criminal custody.

For now, she said, "people are doing what they’ve been doing."

4. How will the courts respond?

A key provision asks Attorney General Jeff Sessions to request that a federal court modify the "Flores settlement," which requires the government to keep immigrant children in the “least restrictive” settings possible. It also prohibits the government from keeping children, even if they are with their parents, detained for more than 20 days.

The request will be filed to federal Judge Dolly Gee, who oversees the settlement.

"It's on Judge Gee," Gene Hamilton, the counselor to Sessions, told the New York Times. "Are we going to be able to detain alien families together or are we not?"

5. What will Congress do?

The order puts the onus on congressional lawmakers to address the situation themselves.

"It is unfortunate that Congress’s failure to act and court orders have put the Administration in the position of separating alien families to effectively enforce the law," the orders reads.

House lawmakers voted down one immigration proposal Thursday that addressed border separations. Another more moderate bill which also addressed immigrant children being separated was pulled from the floor at the last minute Thursday. Members are expected to vote on it Friday.

Trump himself expressed doubts about legislation passing both the Senate and House on Thursday — and used it to push for a rule change in the Senate.

"What is the purpose of the House doing good immigration bills when you need 9 votes by Democrats in the Senate, and the Dems are only looking to Obstruct (which they feel is good for them in the Mid-Terms). Republicans must get rid of the stupid Filibuster Rule-it is killing you!" he tweeted.

Contributing: Gregory Korte, Kevin Johnson, Deirdre Shesgreen, Eliza Collins

WPXI