Some seized documents were so closely held, only the president, a Cabinet-level or near-Cabinet level official could authorize others to know 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,...