They wanted to storm the Michigan government building and, before the November 3 presidential election, kidnap Democratic Governor Gretchen Whitmer, with the ultimate goal of sparking civil war.
The plan was thwarted by the FBI, which arrested six members of the far-right galaxy on charges of terrorism, conspiracy and attempted conspiracy.
In all, 13 people are accused and many of them now face life imprisonment.
The paramilitary group, in possession of firearms and explosives, wanted to trigger the plan during the summer, when Whitmer came into the spotlight for being on Joe Biden's shortlist of vice presidential candidates.
And for this reason it also ended up in the crosshairs of Donald Trump's criticisms, especially when democratic politics in August passed a decree with severe anticoronavirus restrictions, to avoid the spread of infections.
"Free Michigan!", One of the tweets of the American president in those days, when in front of the State Capitol of the Michigan capital, Lansing, hundreds of people, including armed ones, gathered to protest against the lockdown.
Federal agents went into action shortly before the militia, which was expected to have up to 200 men, finished completing the training already underway by carrying out military-type exercises.
While the clandestine meetings to set up the mission took place in the basement of a shop accessible only through a trapdoor hidden under a carpet.
The plan was to hold Whitmer hostage, move her to a safer location in the neighboring state of Wisconsin, and try her for 'treason'.
Both in August and in September, therefore, the house where politics usually spends their holidays was constantly under control by the group of conspirators.
The episode feeds concerns ahead of the November 3 vote, with the risk that the tensions of the election campaign could escalate into criminal episodes.
"We may all disagree on policy, but these differences should never translate into violence," said Matthew Schneider, the Michigan State District Attorney's Eastern District.
"Donald Trump must know that the words he uses matter": this is how Joe Biden commented on the thwarted plan by the FBI to kidnap the Democratic governor of Michigan, Gretchen Whitmer, developed by a group of the far-right galaxy.
Biden expressed solidarity with Whitmer and said the president's 'Free Michigan' tweet sounds like encouragement for these militias.
And he reiterated his criticisms of Trump guilty of not wanting to explicitly condemn the threat of white supremacism.