Previously, Allen was charged with attempting to assassinate US President Donald Trump, transportation of a firearm and ammunition across state lines with intent to commit a felony, as well as using, carrying, brandishing and discharging a firearm during a crime of violence.
Allen, who did not enter a plea during his previous court appearance, faces a sentence of up to life in prison if convicted of trying to kill Trump during the dinner at a Washington hotel on Apr 25.
While security personnel fired multiple times at Allen, he was not shot, the Department of Justice reiterated in its announcement of the additional charge.
Instead, he suffered a minor knee injury after he “fell to the ground, was restrained by law enforcement, and was placed under arrest”, the department said.
The annual dinner draws scores of Washington journalists, celebrities and entertainers.
Trump has traditionally boycotted the dinner but decided to attend this year. He was uninjured in the attempted attack and has called for the dinner to be rescheduled.
