FBI Search at Donald Trump's Mar-a-Lago Sought Classified Nuclear Documents: Report

NICHOLAS KAMM/getty Former President Donald Trump

The FBI agents who executed a search warrant at Donald Trump's Mar-a-Lago home earlier this week were reportedly looking for classified nuclear documents, among other items.

After the former president, 76, announced that the FBI searched his residence at the Palm Beach, Florida, resort on Monday, a source told The Washington Post that the investigation was in regard to sensitive materials, including those pertaining to nuclear weapons.

The specifics of those documents and whether any were recovered remains unknown, although the report emphasized the potential danger of such classified information falling into the wrong hands.

A source with knowledge of the subpoena tells PEOPLE, "I can't tell you anything about nuclear documents. But this is why it's important for the subpoena to be made public. The public needs to know what is or is not in that subpoena."

PEOPLE's request for comment from Trump's team was not immediately returned.

RELATED: AG Breaks Silence on FBI's Mar-a-Lago Search, Says DOJ Has Filed a Motion to Unseal Search Warrant

Joe Raedle/Getty Mar-a-Lago Club

Although Attorney General Merrick Garland said Thursday that the Department of Justice did not intend to publicize the investigation out of respect for Trump's right to privacy, he confirmed that he personally approved the decision to seek a search warrant as a last resort in their investigation.

He also noted that Trump's very public statement in response to the search has prompted the DOJ to file a motion in a Florida court to unseal the search warrant and property receipt, making those details available to the public.

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"The public's clear and powerful interest in understanding what occurred under these circumstances weighs heavily in favor of unsealing," the motion reads, according to The Post. "That said, the former President should have an opportunity to respond to this Motion and lodge objections, including with regards to any 'legitimate privacy interests' or the potential for other 'injury' if these materials are made public."

Garland's speech came as The Wall Street Journal and Newsweek reported that the investigation stemmed from an informant.

RELATED: FBI Director Says Threats Against Agents After Mar-a-Lago Search Are 'Deplorable and Dangerous'

After FBI agents and a senior Justice Department national security supervisor reportedly visited Mar-a-Lago in early June in regards to boxes of classified documents sitting in the property's basement, officials followed up with Trump's lawyer, with instructions to install a stronger lock on the storage room door.

Trump reportedly assured officials that he had no more classified materials, but weeks later, "someone familiar with the stored papers told investigators there may be still more classified documents at the private club."

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Newsweek's reporting echoed that of the Journal, citing two government officials who said that a "confidential human source ... was able to identify what classified documents former President Trump was still hiding and even the location of those documents."

By June 22, the investigation had taken a new turn, with the Journal reporting that the Trump Organization "received a subpoena for surveillance footage from cameras at Mar-a-Lago" (footage it said was ultimately turned over).

Two months after their first visit to the private Palm Beach club, agents were back — this time with a search warrant.

While the FBI conducted its search of the property Monday — which reportedly focused on Trump's office and personal quarters — the former president was in New York City inside Trump Tower.