Ammon Bundy standoff Cliven Nevada Oregon
The group's leader, Ammon Bundy, led a stand off with federal officers for several weeks in 2014 over a two-decades-long grazing rights disputeGeorge Frey/Getty

At the time of writing, some 15 armed men are still occupying a federal government building in Oregon state. They are not terrorists. Or at least, they are not being referred to as terrorists by officials and much of the media. They claim no desire for a violent conclusion to their actions -- but are prepared to kill and be killed for their cause if it comes to that. So who are they?

The so-called "Bundy militia" broke away from a protest of more than 100 people outside the Malheur National Wildlife Refuge headquarters, which sits deep in the rural west, about 30 miles south of the city of Burns, Oregon. They occupied the building in an armed protest against the arson convictions of two local ranchers who were accused of setting fire to public land owned by the federal government. The militia also set up a roadblock and has marksmen in a nearby tower. So far no police or security forces are at the scene, though local and state police say they are monitoring the situation with help from the FBI.

Their leader is Ammon Bundy, a 40-year-old rancher and son of Cliven Bundy, who led a stand off at his Nevada cattle ranch with federal officers for several weeks in 2014 over a two-decades-long grazing rights dispute. He had been accused of using public land for grazing without a licence. The tense stand off ended peacefully, though a legal dispute remains ongoing.

The Bundy militia claims to be enforcing the US constitution by defending individual landowners against the central government, which Cliven Bundy has said he does not recognise as legitimate. Its ideology harks back to before the American Civil War more than 150 years ago, in which the Unionists were triumphant over the Confederacy, when the country was a disparate group of self-governing individual states. The Bundys have found support from within the Tea Party and the Sovereign Citizens movements, both of which hold paranoid views about the power and motivations of central government, and regard it as largely illegitimate.

Dwight Hammond, 73, and his son Steven, 46, were first convicted by a jury of arson on federal lands in Oregon, taking place in 2001 and 2006, in a June 2012 trial lasting two weeks. "By law, arson on federal land carries a five-year mandatory minimum sentence," said the US Justice Department. "When the Hammonds were originally sentenced, they argued that the five-year mandatory minimum terms were unconstitutional and the trial court agreed and imposed sentences well below what the law required based upon the jury's verdicts."

However, the Supreme Court overturned the decision in March 2015 and both men were sentenced again in October, this time to serve a minimum of five years in prison. And it is at this decision that the Bundy militia has taken up arms. They claim the prosecutions of the Hammonds is persecution by the federal government, which wants to seize their land in a conspiracy to make it part of the Malheur National Wildlife Refuge.

"This refuge from its very inception has been a tool of tyranny," said Bundy at a press conference inside the occupied building, reported the Guardian. "Steven and Dwight Hammond would not have been abused the way they have if we had adhered to the constitution. When government steps outside the bounds the people have given it, it is the duty of the people to put it back in its place."

Bundy added that the militia's desire is to return the refuge land back to "ranching, trucks and recreational vehicles like it used to be", and claims that Oregon's economic problems are caused by the taking of its land by the federal government and from the people. He said in a video that the group plans on making the refuge a hub for patriots and they will stay for "several years".

One of the militiamen left a sinister emotional video message in which he appears to say goodbye to his family ahead of the occupation. Jon Ritzheimer is a former US marine and a known anti-Islam protester who led a rally of armed demonstrators outside a mosque in his native Phoenix, Arizona.

"The oppression and the tyranny that has taken place here in Oregon," said Ritzheimer in the video, uploaded to YouTube, "we know it's taking place all across the US. The Bundy ranch was a prime example. And we, the people, need to take a stand." Another of the militiamen rejected the claim that they had set up a roadblock. Blaine Cooper wrote on his Facebook account that it is "a peaceful armed stand for the constitution".

"These men came to Harney County claiming to be part of militia groups supporting local ranchers," Sheriff David M Ward told reporters, "when in reality these men had alternative motives, to attempt to overthrow the county and federal government in hopes to spark a movement across the United States."

The story caused uproar on Twitter under the hashtag #OregonUnderAttack. Many users complained that the group is being referred to as a militia. If they were Muslims they would be called terrorists, it was suggested, but because the group is white, their coverage and treatment by the media has been different and preferential.

Other comparisons were made with the treatment by police officers of black people, in particular the killing of 12-year-old Tamir Rice, who was waving a toy gun in a park. They criticised the hands-off approach of law enforcement to the Bundy militia.

Terrorists, militiamen, freedom fighters: whatever you want to call Bundy's seditious group, the fact remains that some 233 years after the end of the American Revolutionary War; 227 years after the US constitution came into force; and 151 years since the end of the Civil War, there is still a small-but-dangerous rump of Americans willing to take up arms against their own government.