PORTLAND, Ore. (Reuters) - Anti-government militants who invaded a federal wildlife refuge in Oregon conspired to intimidate government workers and steal property in a heavily armed protest that is not protected by the U.S. Constitution, prosecutors said on Tuesday.

Inmates (clockwise from top left) Ryan Bundy, Ammon Bundy, Brian Cavalier, Peter Santilli, Shawna Cox, Ryan Payne and Joseph O'Shaughnessy, limited-government activists who led an armed 41-day takeover of the Malheur National Wildlife Refuge, are seen in a combination of police jail booking photos released by the Multnomah County Sheriff's Office in Portland, Oregon January 27, 2016. Multnomah County Sheriff's Office/Handout via Reuters

Assistant U.S. Attorney Geoffrey Barrow told a packed federal courtroom in downtown Portland that during the January takeover, the conspirators, many wearing camouflage and toting rifles, practiced shooting drills and hand-to-hand combat together at the Malheur National Wildlife Refuge. They also had a stockpile of some 15,000 rounds of ammunition.

“They moved as a military force,” Barrow said, adding later: “We all have a right to bear arms. This is a case about what the defendants did with those firearms.”

Barrow’s remarks came during opening statements in the trial of ranchers Ammon and Ryan Bundy and five other limited-government activists who led the 41-day takeover of the refuge that began on Jan. 2.

The defendants pleaded not guilty to conspiracy to impede federal officers from doing their jobs through intimidation, threats or force, possession of firearms in a federal facility and theft of government property.

The takeover at Malheur was the latest flare-up in a decades-old conflict over federal control of millions of acres of public land in the West.

The Bundy brothers have been at the forefront of that movement and stood by their father, Cliven Bundy, at his Nevada ranch in a 2014 armed standoff with authorities over enforcement of federal grazing rights.

Marcus Mumford, a lawyer for Ammon Bundy, told the court the intent of the peaceful protest was to draw attention to the federal government’s illegal control and mismanagement of public lands, not to intimidate federal employees.

He said Bundy was attempting to invoke a provision of the law known as adverse possession to retake land improperly seized by the federal government many decades ago.

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‘STATE OF MIND’

U.S. District Judge Anna Brown told Mumford arguments over adverse possession were not relevant to the case and similarly rejected Ryan Bundy’s request to hand each member of the jury a pocket-sized copy of the U.S. Constitution.

“You may alert the jury to what the evidence will show as to your state of mind,” Brown said.

Ryan Bundy, who is acting as his own lawyer, took aim at the prosecutor’s theory that the occupation amounted to a conspiracy.

“A conspiracy is when two people act together to conduct a heinous act,” he told jurors. “That is not who I am.”

Barrow, the federal prosecutor, said the Bundys and others blocked outsiders from coming in, used government computers and refused to leave. At one point, a man with a shotgun stood guard from a watchtower.

He also said Ammon Bundy and another protester warned Harney County Sheriff Dave Ward of “extreme unrest” two months before the protest and used social media to draw supporters from across the country.

The Bundys drew supporters inside and outside the courtroom, some of whom wore cowboy hats, and bracelets or T-shirts with patriotic messages or phrases from the Constitution.

More than two dozen people have been charged in connection with the takeover, and a second group of defendants are scheduled to go on trial in February.

Opening statements concluded on Tuesday afternoon. Testimony is due to begin on Wednesday.