Four US soldiers planned to overthrow the federal government and kill President Obama, the Press Association reports. The alleged plot, whose details remain scarce, emerged during a murder case against the soldiers. One of the four, Pfc. Michael Burnett, pleaded guilty to manslaughter and gang charges today in the deaths of an ex-soldier and his girlfriend, 17. The ex-soldier, Michael Roark, was killed because he was aware of the plot, Burnett said. The quartet had purchased $87,000 worth of firearms and explosives; they intended to attack Fort Stewart as well as locations in Georgia and Washington state, the AP reports. Click for our latest story on the plot.