There are "continued calls for violence directed at U.S. critical infrastructure," the agency warned last February, "as a means to create chaos and advance ideological goals."
Law enforcement and utility companies, though, say they're working to resolve the open cases and prevent future attacks.
Members of accelerationist groups have been charged with several plots in recent years to attack critical infrastructure.
"The critical infrastructure element has become one of the core components of neo-fascist accelerationist movements in the US.
"They don't really care who is doing the violence, who's doing the critical infrastructure attacks, Lewis said.