Nine people said to belong to a radical American Christian militia group have been formally accused of waging war against the United States.
The suspects, detained in a series of FBI raids across the Mid-West, have been charged with conspiring to kill police officers, the BBC reports.
Prosecutors say the eight men and one woman were members of a group called Hutaree, described in the indictment as an anti-government extremist organisation advocating violence against police.
It is alleged the group conspired to murder an unidentified police officer and then stage a second attack on the resulting funeral procession using landmines and roadside bombs.
Over the weekend, the FBI raided properties in Michigan, Ohio and Indiana in the belief that the group was planning a reconnaissance exercise.
A statement on the group's website says they are preparing to defend themselves upon the arrival of the Antichrist.