"When the federal Government was stopped from enforcing the law at gunpoint, that energised this entire movement," said Heidi Beirich of the SPLC. "When you have a big win like they did at the Bundy ranch, it emboldens people ... It is definitely a recipe for disaster."
Since running federal officers off his ranch, Bundy and his supporters have become a travelling troop - co-opting various incidents in which they think the federal Government is over-regulating people. In April, the Bundy family involved itself in a dispute at the Sugar Pine Mine, during which a local miner took up arms against federal agents who said he did not own the surface rights to the land he was mining. Other members of the Bundy operation went to the border, arguing that if the federal government would not prevent illegal immigration, they would do it themselves.
And the plight of the Hammond family - Oregon ranchers sentenced to prison for arson - caught the attention of Ammon Bundy, an Idaho rancher who is one of Cliven's sons.
Ammon and one of his brothers, Ryan Bundy, are leading the occupation in Oregon, and have vowed to remain in the federal wildlife refuge until the Hammonds are released from prison.
FBI heads response to Oregon protest
The FBI has taken charge of the response to an armed occupation of a federal wildlife refuge in Oregon, saying that it will work with local and state authorities to seek "a peaceful resolution to the situation".
"Due to safety considerations for both those inside the refuge as well as the law enforcement officers involved, we will not be releasing any specifics with regards to the law enforcement response," the FBI said.
Federal authorities are working with local and state police and agencies in response to the situation in eastern Oregon, the latest chapter in an ongoing fight over federal land use in the West.
The occupation of a remote federal wildlife refuge followed a march and rally held over the weekend to support two local ranchers convicted of arson. The two ranchers - Dwight Hammond and his son, Steven - turned themselves in, to report to federal prison.
After the march, a group of armed activists, led by rancher Ammon Bundy, travelled to the Malheur National Wildlife Refuge and announced plans to stay indefinitely.
Although Bundy's father, Cliven, told a reporter in Oregon that "150 militia men" had occupied the federal land, at least one person who saw them leave for the refuge said there were "maybe a dozen" people.
President Barack Obama is aware of the Oregon situation, but the White House considers it "a local law enforcement issue," press secretary Josh Earnest said.
- Washington Post, Bloomberg