The Department of Homeland Security issued a national terrorism bulletin on Wednesday, warning of the potential for violence from people motivated by anti-government sentiment.
It suggested that the January 6 riot at the Capitol in Washington DC may embolden extremists and set the stage for more attacks.
The department did not mention a specific threat, but pointed to “a heightened threat environment" across the US, which it believed persisted even after President Joe Biden took office on January 20.
"Information suggests that some ideologically motivated violent extremists with objections to the exercise of government authority and the presidential transition, as well as other perceived grievances fuelled by false narratives, could continue to mobilise to incite or commit violence," the bulletin said.
It did not mention any ideological or political affiliation.
It is not uncommon for the federal government to warn local law enforcement through bulletins and advisories about the possibility of violence tied to a particular date or event, such as July 4.
But this bulletin, issued through the department’s National Terrorism Advisory System, places the Biden administration in the politically charged debate over how to classify acts motivated by political ideology.
It suggests that it considers violence aimed at overturning the election as being akin to terrorism.
The wording of the document suggests that security officials see a connection between violence over the past year that was motivated by anti-government grievances, such as Covid-19 restrictions, the 2020 election results or police use of force.
It also singles out racially motivated acts of violence, such as the 2019 rampage against Hispanics in Texas, and the threat posed by extremists motivated by foreign terrorist organisations.
The alert came only weeks after the riot at the Capitol by supporters of former president Donald Trump, who were seeking to overturn the results of the presidential election.
The bulletin also notes violent riots in “recent days", apparently referring to events in Portland, Oregon, linked to anarchist groups.
The alert was issued by acting Homeland Security Secretary David Pekoske.
Mr Biden's nominee for the Cabinet post, Alejandro Mayorkas, has not yet been confirmed by the Senate.