Acting AG Todd Blanche said the case was investigated for months, adding "it's serious when you threaten the president."
Claire Finkelstein says Comey will likely fight his indictment over a social media post critical of Trump.
Trump has long called for prosecution of Comey, who led an FBI investigation related to the president's 2016 campaign.
The indictment stems from a 2025 photo of seashells posted by Comey that critics have said encouraged violence against the US president.
Former FBI director James Comey was indicted on Tuesday in an investigation over a social media photo of seashells arranged on a beach that officials said constituted a threat against US President Donald Trump, according to a person familiar with the matter. The person was not authorised to publicly discuss the matter and confirmed the indictment on the condition of anonymity. The charge or charges against Comey were not immediately known. It is the second criminal case the Justice Department...
They have been indicted by a federal grand jury with one count of conspiracy to commit visa fraud in connection with a conspiracy to carry out staged armed robberies at convenience stores