A member of the Oath Keepers extremist group was sentenced to eight and a half years in prison for participating in the riot at the US Capitol on 6 January 2021.
Jessica Watkins was convicted in November by a federal jury in Washington DC of obstruction of an official proceeding after storming the Capitol, which saw rioters battle police, smash windows and enter the Senate.
Watkins was also convicted of conspiracy and obstruction of officers during the riots.
US District Judge Amit Mehta said it was "particularly hard" to issue a sentence, following testimony during the trial about Watkins' struggles with being transgender and cooperation with law enforcement during their investigation.
However, he said that "doesn't wipe out" Watkins actions during the attack.
"Your role that day was more aggressive, more assaultive, more purposeful than perhaps others," Judge Mehta added.
Kenneth Harrelson, another Oath Keeper convicted of obstruction of an official proceeding, was also found guilty of conspiring to prevent members of Congress from certifying President Joe Biden's election win as well as tampering with documents and proceedings.
He will be sentenced later.
Watkins and Harrelson were both acquitted of seditious conspiracy charges.
Federal prosecutors had asked Judge Mehta in Washington to sentence Watkins to 18 years in prison.
During tearful remarks in court, Watkins asked Judge Mehta to issue a just sentence saying: "My actions and my behaviour that fateful day were wrong and, as I now understand, criminal."
Federal prosecutor Alexandra Hughes told Judge Mehta that the actions of Watkins and other Oath Keepers on that day "were not an aberration" and that a significant sentence should be imposed.
Watkins' lawyer asked for a sentence of five years in prison.
Prosecutors are seeking a 15-year sentence for Harrelson.
Harrelson and his lawyers have not suggested a sentence and he maintains his innocence.
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Friday's court proceedings are taking place one day after Judge Mehta sentenced Oath Keepers' founder Stewart Rhodes to 18 years in prison for crimes including seditious conspiracy or using force to try to overthrow the federal government.
That is the steepest penalty yet against those charged over the Capitol riot.
Members of the Oath Keepers, founded by Rhodes in 2009, include current and retired U.S. military personnel, law enforcement officers and first responders.
They have appeared, often heavily armed, at protests and political events including demonstrations that followed the 2020 murder of George Floyd.
Some Oath Keepers, including Watkins and Harrelson, breached the Capitol clad in paramilitary gear.
Others at a suburban hotel staged a "quick reaction force" prosecutors said was equipped with firearms that could be quickly transported into Washington.
Four other Oath Keepers members convicted of seditious conspiracy in a second trial are due to be sentenced next week.