Under President Donald Trump, ICE—the law enforcement agency that arrests and deports undocumented immigrants—has quietly grown closer to at least one of America’s intelligence agencies, according to a letter from a top American intelligence official reviewed by The Daily Beast.

The change, which came behind closed doors and without fanfare, has concerned civil liberties advocates. And the Department of Homeland Security, which houses ICE (Immigration and Customs Enforcement), isn’t answering questions about it.

The revelation came in a letter that David Glawe, DHS’ undersecretary for intelligence and analysis, wrote to Congress late last year. This letter, the contents of which have not been previously reported, sheds new light on ICE’s relationship with the 17 U.S. government organizations that collect and analyze intelligence, known collectively as the Intelligence Community or IC. But the letter also raises a host of questions.

“ The public should know far more about any ‘improved and enhanced’ intelligence capabilities DHS has developed. ” — ACLU's Patrick Toomey

Glawe wrote the letter in response to an inquiry that Reps. Michael McCaul and Bennie Thompson—then the chairman and ranking member of the House Committee on Homeland Security—sent to then-DHS Sec. Kirstjen Nielsen on Sept. 28, 2018. In McCaul and Thompson’s letter, which The Daily Beast also reviewed, the members asked about the aspirations of ICE and Customs and Border Protection (CBP) officials to join the Intelligence Community (The Daily Beast was the first to report about those aspirations). Their letter asked how the potential change might benefit national security.

Glawe’s response, dated Nov. 13, 2018, said he and Nielsen had vetoed ICE and CBP’s plans to join the Intelligence Community.

“The Secretary of Homeland Security and I agree that this is not the right time to pursue potential IC membership for CBP and ICE,” he wrote.

Then Glawe detailed his work to reorganize the Office of Intelligence and Analysis (I&A), the component of DHS that belongs to the IC. Glawe has prioritized this effort—which has frustrated some career officials in the office. As part of that reorganization, the branch of the office that focused on domestic terrorism was eliminated. Glawe said this change has not hindered DHS’ ability to prevent domestic terror attacks but multiple sources in DHS have told The Daily Beast the change concerns them. And member of Congress have said they share those fears.

In the letter, Glawe wrote that cooperation between I&A and ICE has grown. He made this revelation in a wordy, vague paragraph laden with intel jargon:

As a result of this realignment, as well as our ongoing efforts to integrate DHS field and functional intelligence activities into a fully synchronized and cohesive enterprise; I&A is providing improved and enhanced intelligence capabilities to DHS components, including ICE and CBP, as well as the interagency. These capabilities include collection, reporting, and analysis to support a DHS enterprise that fuses intelligence into operational functions, disciplines, and activities to inform actions that neutralize threats to the homeland. The cumulative impact of these efforts are more focused and integrated intelligence capabilities and products which meet customer requirements.

Read literally—as these letters should be—Glawe’s letter says ICE has received “enhanced intelligence capabilities,” including collection. “Collection” refers to the process of gathering information and intelligence. Some collection methods generate acute concern among civil liberties advocates. Perhaps the most notable in recent memory was the NSA’s bulk collection of information about Americans’ communications with each other. The IC reduced its use of one of those programs, authorized under Section 215 of the Patriot Act, after Edward Snowden exposed it. Another surveillance authorization—known as 702, for a section in the Foreign Intelligence Surveillance Act—lets the NSA hoover up Americans’ personal email communication. Congress reauthorized it last year, after a contentious debate that Trump himself almost torpedoed.

So Glawe’s letter raises questions.

“I’m curious about the phrases ‘fuses intelligence into operational functions’ and ‘activities to inform actions,’ which sound like there is some type of information sharing arrangement going on,” said Jake Laperruque, a lawyer for the Project on Government Oversight who focuses on privacy and surveillance. “If information is coming from PATRIOT Act Sec. 215 or FISA Section 702, that would be a huge controversy.”

“The public should know far more about any ‘improved and enhanced’ intelligence capabilities DHS has developed,” said Patrick Toomey, a senior staff attorney on the ACLU’s National Security Project. “It’s vital that the public understand the kinds of sensitive information that DHS may be collecting and analyzing—including whether ICE is relying on any expanded spying or data-mining capabilities for domestic immigration enforcement.”

The Daily Beast emailed a few questions to the top DHS spokespersons several days before publication: What kind of enhanced capabilities does ICE now have? Is ICE collecting publicly available information, private information, or both? Does any of the collection involve scanning people’s social media accounts?

The Daily Beast received no response to multiple follow-up emails, and will update this story if we do. To be fair, DHS’ public affairs section has been slammed over the last week; on April 5, President Donald Trump tweeted that Nielsen’s tenure at the Department would end. In the days after, a spate of top officials left the department, including Claire Grady, who had been third-in-command; and the chief of the Secret Service. The White House also abruptly withdrew its nominee to head ICE.

On top of all that, The Washington Post reported on April 11 that the White House has pushed DHS to release detained undocumented immigrants into so-called sanctuary cities, in some effort to punish cities that don’t cooperate with ICE. Trump quickly confirmed the reporting, and White House officials said talks about such a move are underway.

Public brawls, fights, and firings have drawn more attention than ever to DHS. But the quiet changes it doesn’t talk about may be among the department’s most enduring.