Washington (CNN) They're carrying out sporadic terror attacks on police, have threatened attacks on government buildings and reject government authority.

A new intelligence assessment, circulated by the Department of Homeland Security this month and reviewed by CNN, focuses on the domestic terror threat from right-wing sovereign citizen extremists and comes as the Obama administration holds a White House conference to focus efforts to fight violent extremism.

Some federal and local law enforcement groups view the domestic terror threat from sovereign citizen groups as equal to -- and in some cases greater than -- the threat from foreign Islamic terror groups, such as ISIS, that garner more public attention.​

The Homeland Security report, produced in coordination with the FBI, counts 24 violent sovereign citizen-related attacks across the U.S. since 2010.

The government says these are extremists who believe that they can ignore laws and that their individual rights are under attack in routine daily instances such as a traffic stop or being required to obey a court order.

They've lashed out against authority in incidents such as one in 2012, in which a father and son were accused of engaging in a shootout with police in Louisiana, in a confrontation that began with an officer pulling them over for a traffic violation. Two officers were killed and several others wounded in the confrontation. The men were sovereign citizen extremists who claimed police had no authority over them.

Among the findings from the Homeland Security intelligence assessment: "(Sovereign citizen) violence during 2015 will occur most frequently during routine law enforcement encounters at a suspect's home, during enforcement stops and at government offices."

DHS has documented examples of violence by sovereign citizen extremists since 2010. They range from incidents that occurred in the home and at traffic stops to attacks on government buildings.

The report adds that "law enforcement officers will remain the primary target of (sovereign citizen) violence over the next year due to their role in physically enforcing laws and regulations."

The White House has fended off criticism in recent days for its reluctance to say the words "Islamist extremism," even as the conference this week almost entirely focused on helping imams and community groups to counteract the lure of groups like ISIS.

Absent from the White House conference is any focus on the domestic terror threat posed by sovereign citizens, militias and other anti-government terrorists that have carried out multiple attacks in recent years.

An administration official says the White House is focused on the threat from all terrorists, including from sovereign citizen and other domestic groups.

"I don't think it's fair to say the (White House) conference didn't address this at all," the official said, adding that President Barack Obama addressed the need to combat "violent ideologies" of all types.

An official at the Justice Department, which is leading the administration's counter-radicalization effort, says many of the tactics aimed at thwarting radical Islamic recruitment of young people can also be used to fight anti-government extremist groups.

While groups like ISIS and al Qaeda garner the most attention, for many local cops, the danger is closer to home.

A survey last year of state and local law enforcement officers listed sovereign citizen terrorists, ahead of foreign Islamists, and domestic militia groups as the top domestic terror threat.

The survey was part of a study produced by the University of Maryland's National Consortium for the Study of Terrorism and Responses to Terrorism.

In 2013, a man who held anti-government views carried out a shooting attack on three Transportation Security Administration employees at Los Angeles International Airport, killing one TSA officer. Last year, a couple killed two police officers and a bystander at a Las Vegas Walmart store.

Officers inspect a car outside Los Angeles International Airport in 2013 after three TSA employees were shot.

Mark Potok, senior fellow at the Southern Poverty Law Center, said that by some estimates, there are as many as 300,000 people involved in some way with sovereign citizen extremism. Perhaps 100,000 people form a core of the movement, he said.

The federal government's focus on the domestic groups waxes and wanes, Potok said, in part because the threat from foreign groups like al Qaeda and its affiliates.

Potok says sovereign citizen groups have attracted support because of poor economic conditions. Some groups travel the country pitching their ideology as a way to help homeowners escape foreclosure or get out of debt, by simply ignoring the courts and bankruptcy law.

The Homeland Security report's focus on right-wing terrorists is a subject that garnered political controversy for the Obama administration in the past. In 2009, a Homeland Security report on possible recruitment of military veterans by right-wing militia groups prompted an outcry from veterans groups.

The report was produced by staff members during the Bush administration but wasn't published until then Homeland Security Janet Napolitano had taken office. Napolitano criticized her own agency for the report.