The US remains in a "heightened threat environment" for terrorism driven by a series of racially and ethnically motivated attacks or plots in recent months, the Department of Homeland Security said Wednesday in a public advisory.
The pro-Nazi views espoused by the gunman who killed eight people in Allen, Texas, this month are part of a growing trend of extremists displaying White nationalist paraphernalia in the US and abroad, a senior DHS official told reporters.
On online forums, "there does seem to be an increase in the calls for violence based on the neo-Nazi, White nationalist theme," a second DHS official said during a briefing that the department held on the condition that officials not be quoted by name.
The DHS officials said they were still assessing an incident Monday night in which a man crashed a U-Haul truck into a security barrier near the White House and, according to court documents, praised Adolf Hitler to investigators after his arrest.
The National Terrorism Advisory System Bulletin is the main way that DHS updates the public every few months on terrorism threats. The new bulletin issued Wednesday mirrors the previous one from last November, in which officials were concerned by lone-wolf attackers motivated by a range of ideologies.
DHS officials also said they were watching the run-up to the 2024 US presidential election for signs of extremist violence in light of the deadly January 6, 2021, insurrection.
While there were no immediate or specific threats involving the 2024 election to report, if extremists start to discuss the potential outcomes of the 2024 election in terms of "existential" or "apocalyptic" terms, "that obviously would heighten our concern that individuals may act on that sense of existential threat," the first DHS official told reporters.
"Any narrative that gains traction in the public domain that casts doubt on the legitimacy of elections ... would contribute to the potential for" violent extremist acts, the official said.
White supremacists and other extremists have been implicated in multiple attacks against electrical substations and other US critical infrastructure in the last year. Two white supremacists were arrested in February for an alleged racist plot to attack the power grid in Baltimore.
Extremists have increasingly shared tactics with each other on using guns to attack electric power stations in a move that likely escalates the threat to US critical infrastructure, according to a private DHS analysis issued last month that CNN obtained.
The new DHS bulletin issued Wednesday also warns that foreign terrorists continue to call for lone-wolf attacks in the West. DHS pointed to an attack by a man from Maine on New York police officers on New Year's Eve. The man carried a handwritten diary that expressed his desire to join the Taliban in Afghanistan, CNN previously reported.