The former president -- and the favorite to fight next year's election for the Republicans -- gave himself up to U.S. Marshals in Miami for a brief hearing that set up the unprecedented scenario of a White House race litigated from the courtroom as well as at the ballot box.
On the eve of his 77th birthday, Trump appeared before a magistrate judge to be formally presented with 37 charges brought by a special counsel probe that opened after an FBI raid of his Florida mansion.
"We are certainly entering a plea of not guilty," Todd Blanche, his attorney, told the hearing.
The hearing -- just weeks after Trump denied state level financial fraud charges in a separate case in Manhattan -- came with the former reality TV star's mounting legal woes threatening to derail his bid to return to the Oval Office.
The US government accuses Trump of violating the Espionage Act and other laws when he removed classified documents upon leaving office in 2021 and failed to give them up to the National Archives.
Authorities say he conspired to thwart investigators and knowingly shared national security secrets with people who did not have the requisite clearance.
Trump was heading back to his golf club in Bedminster, New Jersey, to deliver an evening speech protesting his innocence -- but not before stopping to greet supporters at a Cuban restaurant in Miami's Little Havana, where they sang happy birthday in his honor.
"We have a country that's corrupt," Trump told the gathering, railing at the charges brought against him.
"A country in decline like never before," he said. "I think it's a rigged deal here."
Miami officials were preparing for large scale protests, and police had ramped up security well in advance of what turned out to be a few dozen Trump supporters converging near the courthouse.
Some wore "Make America Great Again" baseball caps and one with a sign reading "Indict Jack Smith" -- the special prosecutor who brought the charges.
Trump himself lashed out at Smith on his Truth Social network earlier, calling the prosecutor a "thug" and a "lunatic."
'Ridiculous'
The runaway frontrunner in the 2024 Republican primary has vowed to stay in the race regardless of the outcome of the documents case.
The 49-page indictment, dismissed by Trump as "ridiculous," includes photographs showing boxes of documents stacked at Mar-a-Lago, his Palm Beach residence, in a ballroom and in a bathroom and shower.
Trump, who leads the Republican race for president by more than 30 points, has been impeached twice over allegations of misconduct in office and was recently found liable for sexual abuse.
He faces indictment or ongoing scrutiny in four criminal probes -- in Washington, Florida, Georgia and New York -- and could find himself on trial in multiple cases as he campaigns to return to the White House.
The pugnacious billionaire continues to defend and even praise the rioters who ransacked the Capitol to halt the certification of the 2020 election, and has promised pardons for many if he is reelected.
Trump -- who has repeatedly complained that the investigations against him amount to a baseless "witch hunt" -- vowed Monday to appoint a special prosecutor on his return to office to investigate President Joe Biden and his family.
He appeared in court with strong backing from Republican voters, 81 percent of whom believe the charges against the former president are politically-driven, according to a new Ipsos poll.
"In recent years we have seen the rise of politically-motivated prosecutors who don't care for impartiality, who don't care for due process or equal protection of laws," Trump lawyer Alina Habba told CNN.
"They have been quietly but aggressively cultivating a two-tiered system of justice where selective treatment is the norm."
Republican leaders in Congress and Trump's rivals for the party's presidential nomination have largely glossed over the gravity of the allegations against him, instead attacking the Justice Department.
The pro-Trump super PAC MAGA Inc launched an ad Monday noting that an ongoing investigation into Biden's own handling of classified documents has not yielded an indictment.
The two cases bear few similarities as Biden is not accused of refusing to return classified documents or suspected of thwarting government attempts to recover them.