Right-wing domestic terrorism has a history of surging following the election of liberal Democratic presidents. Bigotry, religious intolerance, ignorance and a misguided, heightened  sense of patriotism all play an important in domestic terrorism. 

In the 1930s, as in the 1960s and 1990s, conservative critiques painted liberal administrations as not just naive or weak but actively treacherous, plotting to sell out the country to its enemies. Facing such a threat -- however imaginary -- radicals resorted to the age-old American tradition of taking up arms to resist tyranny. Witness the very name of the Minutemen.

Could it happen again? Imagine a scenario in which a Democratic administration withdrew from Iraq, and conservatives denounced the betrayal of sacrifices made by the armed forces. Then consider all the personnel who have cycled through private security firms in Iraq and elsewhere, whose knowledge of military organization and weaponry could make them an effective nucleus of a new militia movement. If a disintegrating economy were fueling popular fear and unrest, the elements would be in place.