(The Hill) — The revelation that former President Donald Trump had some of the nation’s most closely guarded forms of intelligence at his Florida home is renewing questions over the potentially grave risks to U.S. national security.

The affidavit used to secure a search warrant for Trump’s home released Friday reveals why the government was so alarmed: Among an initial batch of 184 classified documents retrieved from Mar-a-Lago in January were secrets gained from “clandestine human sources,” information prohibited from being shared with foreign governments and information obtained by monitoring “foreign communications signals.”

Finding 25 sets of highly classified materials was enough to spur the Justice Department — after months of failed negotiations and a subpoena to Trump — to seek a search warrant, securing another 11 sets of documents that included more highly sensitive materials.

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The Office of the Director of National Intelligence (ODNI) alerted lawmakers over the weekend that it would begin work on a damage assessment to evaluate the fallout from what the Justice Department in June told Trump’s legal team were documents not “handled in an appropriate manner or stored in an appropriate location.” 

Former intelligence officials describe a painstaking process that will involve officials evaluating whether the classified documents were compromised and by whom in order to take steps to prevent further damage.

“They will proceed from the worst-case assumption: that any/all of the classified material could have been exposed to a sophisticated adversary intelligence service, and look at the documents from the standpoint of what can be gleaned about what the US knows (or doesn’t know) about a given topic,” James Clapper, who served as director of national intelligence under the Obama administration, wrote in an email to The Hill.

Clapper also said the intelligence community will need to examine the “chain of custody” of the documents, which will involve evaluating how they were handled since they were in the White House and by whom as well as who had access to the documents and whether they were photographed or copied.

The federal government has strict rules governing classified information, and the Justice Department has prosecuted individuals for unauthorized disclosures of the nation’s secrets. 

A search warrant unsealed earlier this month suggested that the Mar-a-Lago search is linked to an investigation of possible violations of the Espionage Act, in addition to other laws. 

In an interview, former Director of National Intelligence Dan Coats, who served under Trump, recalled instructions he received when he entered government about not being able to publicly release classified documents without proper certification and the prohibition against moving classified information outside government buildings or taking it with you when you leave service.

“You don’t want to breach that requirement,” he said. “It can be dangerous if some of that is not handled the way it’s supposed to be handled.”

“Everybody knows that coming in. I’m sure the president was reminded of that by his legal team,” Coats said.

There is little known about the documents themselves, but experts say the classification markings disclosed in the unsealed documents suggest the information could present a severe danger were it to fall into the wrong hands. 

“That tells me that, by legal definition of top secret, somebody in a position of authority and knowledge classified that material because they thought its disclosure of such information could reasonably be expected to cause exceptionally grave damage to the national security — that is the definition in the Executive Order of Top Secret material,” said Steven Cash, a lawyer at Day Pitney specializing in national security who served at the CIA.

A letter from Director of National Intelligence Avril Haines to the chairs of the House’s Oversight and Reform Committee and Intelligence Committee indicates the agency that oversees the nation’s 18 intelligence agencies will begin a “classification review” of the documents, including an “assessment of the potential risk to national security that would result from the disclosure of the relevant documents.”

It’s a remarkable effort made all the more extraordinary by the unusual circumstances. 

Such assessments usually follow the known leak of information. But in this case, it’s not clear who may have accessed the documents.

Mar-a-Lago may have an exclusive membership list, but it’s hardly the restricted area the intelligence community seeks for cordoning off classified materials, with members of the public on-site to play golf.

Reporting from the Pittsburgh Post-Gazette recently noted a woman under FBI investigation after posing as a wealthy socialite was spotted on the grounds at Mar-a-Lago, taking a photo with Trump and Sen. Lindsey Graham (R-S.C.) on the course. 

The Justice Department subpoenaed security footage from Mar-a-Lago in June. But the footage goes back only about 60 days, according to reporting from The New York Times, and it’s not apparent how extensive the footage is and whether it includes video of the room or rooms where the documents were stored.

Experts warn the intelligence community may not be able to perform a full-fledged damage assessment, which usually requires producing a report detailing what information leaked, steps to mitigate the damage, and how to stop something similar from happening again.

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“The utility of conducting a damage assessment here is overstated for two reasons. One is they’re not going to have good clarity on who accessed the documents, which is critical to assessing damage. And then, two, most assessments look at ‘lessons learned’: How did this happen? And how can we prevent it from happening again? There’s no good answer to that question here. You can’t just say we won’t share sensitive intelligence with the president in the future if he’s someone like Trump. That’s not viable in our system of government,” said Brian Greer, a former CIA attorney.

But even if ODNI undertakes a less formal review, it still has questions to answer, mainly in an effort to protect numerous sources of information — including informants — that are now likely at risk. 

“Separate from a formal damage assessment, the IC [intelligence community] will also consider near-term risk mitigation measures. Do they need to undertake some sort of immediate damage control effort? For instance, if there was information in the documents that could identify a human source, do we need to pull the source? Do we need to exfiltrate them? Or do we just need to at least give them a warning so they can stand down on meeting with their handlers for a little while? Do we need to go cover our tracks?” Greer said. 

“And then the same thing with a surveillance platform. Do we need to consider taking it down so that an adversary can’t discover it?” he added.

The intelligence community has had access to some of the tranche of documents stored at Trump’s home since May. 

But the recovery earlier this month adds another batch of documents to the 184 already shared by the Justice Department. 

Greer warns, however, that the damage is already done.

“They’re going to err on the side of caution. In the absence of concrete information about who accessed the documents, they’re going to have no choice but to assume a compromise and take proactive measures to protect our sources and collection capabilities,” he said.

“That step alone will harm national security,” he added.