Three men with ties to white supremacist groups were sentenced to prison last month for planning to attack a power grid in the northwestern United States.

Last year, federal law enforcement officials charged two people with conspiracy to destroy an energy facility and accused them of creating a racist plot to cut power in Baltimore, a predominantly Black city.

And in February 2022, three men also connected to white supremacist groups pleaded guilty over a scheme to target substations around the country in an attempt to cause “economic distress and civil unrest,” according to the F.B.I.

These plots, though unsuccessful, are part of a larger trend by far-right extremist groups in recent years to try to create chaos by bringing down the energy infrastructure that keeps society functioning, according to experts in extremism.

Plots from white supremacists became more common.

There is a long history of extremist attacks on critical infrastructure in the United States. Of attacks on the energy sector made in the last half-century, most were carried out by unidentified actors. Where assailants were identified, a third of attacks were carried out in the 1970s by people associated with the New World Liberation Front, a left-wing extremist group, according to the National Consortium for the Study of Terrorism and Responses to Terrorism.

But more recent plotted attacks on the energy sector have emerged from the opposite political extreme.