Three men pleaded guilty on Wednesday for their roles in conspiring to attack U.S. power grids, as part of a plot motivated by white supremacy to sow civil unrest and economic distress, the U.S. Justice Department said.

Christopher Cook, 20, of Columbus, Ohio; Jonathan Frost, 24, of Katy, Texas and of West Lafayette, Indiana; and Jackson Sawall, 22, of Oshkosh, Wisconsin each pleaded guilty to one count of conspiring to provide material support to extremists, court documents filed in the U.S. District Court for the Southern District of Ohio showed.

The case comes at a time when Justice Department officials have pointed to an increase in domestic threats stemming from white supremacists and anti-government militias.

In January, the department announced the formation of a new domestic terrorism unit, amid a growing realization that extremists within the country represent a threat on par with that posed by foreign militant groups such as Islamic State.

The defendants, whose representatives could not immediately be reached for comment, face a maximum penalty of 15 years in prison.

Prosecutors say that in the fall of 2019, Frost and Cook hatched their plans in an online chat group, with Frost concocting the idea of attacking a power grid. Within weeks, the two began efforts to recruit others to join in their plan, and Sawall later joined the conspiracy, the prosecutors say.

Their plan was to attack substations, or power grids, with powerful rifles and they believed it would cost the government millions of dollars while causing unrest, the Justice Department said.

"They had conversations about how the possibility of the power being out for many months could cause war, even a race war", the department said in a statement.

As their plan advanced, prosecutors say they met in Columbus, Ohio in February 2020 to train. Frost allegedly provided Cook and Sawall with "suicide necklaces" laced with fentanyl they could ingest if they were caught by law enforcement.

They also are accused of painting a swastika flag under a bridge at a park.

Their plot to carry out their mission in Ohio was derailed during a traffic stop, in which Sawall tried to swallow his suicide pill. He ultimately survived.

Cook and Frost, however, continued traveling onward to Texas where they attempted to recruit juveniles to help their cause, prosecutors say.