A document describing a foreign government’s military defenses, including its nuclear capabilities, was found by FBI agents who searched former president Donald Trump’s Mar-a-Lago residence and private club last month, according to people familiar with the matter, underscoring concerns among U.S. intelligence officials about classified material stashed in the Florida property.

Some of the seized documents detail top-secret U.S. operations so closely guarded that many senior national security officials are kept in the dark about them. Only the president, some members of his Cabinet or a near-Cabinet-level official could authorize other government officials to know details of these special-access programs, according to people familiar with the search, who spoke on the condition of anonymity to describe sensitive details of an ongoing investigation.

Documents about such highly classified operations require special clearances on a need-to-know basis, not just top-secret clearance.

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