Militia attack groups want to ‘blow up Capitol’ during Biden speech, police chief warns

Militia groups involved in the 6 January insurrection want to stage another attack around Joe Biden’s upcoming address to Congress, aiming to “blow up” the complex and kill lawmakers, the acting chief of the US Capitol police has warned.

In alarming testimony to a House subcommittee, Yogananda Pittman said that threats were circulating that directly targeted the president’s first formal speech to a joint session of Congress. A date for the event has not yet been announced.

“We know that members of the militia groups that were present on January 6 have stated their desires that they want to blow up the Capitol and kill as many members as possible,” Pittman said.

Related: Trump's useful thugs: how the Republican party offered a home to the Proud Boys

The police chief’s warning was made in the context of her trying to justify to Congress why exceptional security measures put in place in the wake of the 6 January assault needed to remain until alternatives could be devised. A large area around the Capitol is still surrounded by a 7ft non-scalable fence, and thousands of national guard members continue to be deployed.

“Based on that information, we think that it’s prudent that Capitol police maintain its enhanced and robust security posture until we address those vulnerabilities going forward,” she said.

Her words are also likely to be taken seriously as a clear indication of the ongoing threat posed by the armed militia members who took part in the storming of the Capitol in which five people died and almost 140 police officers were injured. Ashli Babbitt, a Trump supporter and military veteran, was shot and killed by a Capitol police officer.

Several of the most prominent armed militia and extremist groups in the US were at the forefront of the Capitol riot. The assault followed an incendiary rally by Donald Trump to promote his “big lie” that the November election was stolen from him by Biden.

A number of militia members have been arrested and charged as part of the giant federal investigation into the events of 6 January. In an indictment handed down last week against six alleged members of the Oath Keepers militia, the justice department charged that the group had planned for several months to prevent Congress from certifying the electoral college results of the presidential election.

Several members of the far-right Proud Boys have also been charged with criminal conspiracy.

This week’s congressional hearings are the start of what is expected to be a slew of official investigations into the drastic security failures that gave rise to the breach of the Capitol complex. In her testimony Pittman confirmed that some 800 rioters had entered the building and that the total number who were present amounted to as many as 10,000.

Pittman has stepped up to lead the Capitol police force after the chief at the time of the storming, Steven Sund, resigned days after the catastrophe. In his evidence to Congress earlier this week, Sund said: “These criminals came prepared for war.”

The FBI and other law enforcement agencies are tracking closely far-right online chatter for early warnings on any possible repeat attacks in Washington or other cities. In addition to Biden’s upcoming congressional address, law enforcement will also be on alert on the days leading up to 4 March – the date set by the extreme conspiracy theory QAnon for Trump to return to Washington to start a second term as president.

Followers of the crank movement have been growing increasingly agitated by the fantasy around a Trump comeback on 4 March, the date on which US presidents were originally inaugurated.