Defense Secretary Jim Mattis has asked the services to report to him on whether their forces are facing immigration challenges, and said Monday that he has already received an initial briefing on the issue.

Mattis’ query to the services came after a series of stories by Military Times on the deportation fears of active duty and veteran service members. Those families fear that under the stricter enforcement of immigration laws under President Donald Trump’s administration, spouses who are residing in the U.S. illegally will be deported – even possibly as their military family member is deployed.

In March, Mattis told reporters he would check on whether deportation protections for service members or veterans that he highlighted in February would apply to their spouses. On Monday, Mattis said “we are looking at it. We have not yet found a policy that aligns with that. But we are continuing to work it,” he said referring to the protections.

In the interim, Mattis said, “what it’s required us to do, is go out to our forces and check” on the issue, he said. While some information has come in, and he has received an initial briefing on the issue, other units have not known how to respond, Mattis said.

“Because there’s not been a problem in those units, so there’s a little bit of ‘What are they talking about?’” Mattis said. “So we’re not taking that as a good answer. We’ll make certain we’ve got a real answer. That’s still ongoing. I’ve been briefed but it’s still ongoing. So we’ll keep searching.”

In a statement, U.S. Immigration and Customs Enforcement, or ICE, said it “respects the service and sacrifice of those in the military and the families who support them, and is very deliberate in its review of cases associated with veterans and active-duty service members. Any action taken by ICE that may result in the removal of an individual with military service must be authorized by the senior leadership in a field office, following an evaluation by local counsel.”

However ICE could not provide statistics on how many former service members, military spouses or dependents have been the target of deportation proceedings.

While individual case files could indicate whether a person being deported either served in the military or is the spouse or dependent of someone who served, the Department of Homeland Security does not track overall statistics on the numbers of veterans or military spouses who have been removed from the U.S., a DHS official said on the condition of anonymity.

American Families United, an immigration advocacy group, estimates there are as many as 11,800 military families that potentially face deportation proceedings.

Military service has been a path toward citizenship throughout the nation’s wars. Service members do not have to be U.S. citizens, but in order to enlist, they do have to have legal residency in the U.S. at the time of enlistment.

If a veteran does not become a U.S. citizen and commits a crime, he or she can still be deported despite their military service.

For current service members who are not yet U.S. citizens, it is not clear if the administration is still processing military naturalizations. In October 2017 Mattis issued a memo directing that the services are to conduct additional background checks prior to clearing service members to pursue naturalization.

U.S. Citizenship and Immigrations Services, or USCIS, quarterly data that has been previously available, that would show how many service members were naturalized in the first three months since Mattis’ memo, was due last month based on past agency performance. The data has not yet been updated.

In the past, spouses of service members in the U.S. illegally had the option to get reprieve from the government to adjust their legal status without having to leave the U.S. through the “parole in place program.” USCIS is still working on a Military Times’ query as to how many, if any, parole in place waivers have been granted in the current administration.