The Pentagon, the headquarters of the US Department of Defense, is seen from the air on January 24, 2017.
CNN  — 

In an ongoing effort to tackle extremism within military ranks, the Pentagon is putting forward a clearer, sharper definition of extremist behavior, updating the older guidance that was considered too vague on what was and was not allowed.

The results of the Countering Extremism Working Group, including a report on extremism within the Defense Department, come nearly a year after the January 6 insurrection at the US Capitol thrust the issue of extremism within the military to the forefront.

Like the previous rules, the new guidance doesn’t prohibit membership in an extremist organization, but officials said it makes it very difficult to participate.

“Any way that someone could sort of actively become a member of an extremist organization, we’ve accounted for them,” one senior defense official said. “We don’t think there is a way to be a member of an extremist organization in any meaningful way.”

Senior defense officials who briefed reporters Monday said the new guidance also provides a two-part test to determine whether something is prohibited extremist activity. The first question is whether the conduct itself rises to the level of extremist activity, while the second assesses whether there was active participation, the officials said.

The new definitions and guidance do not prohibit additional behavior – what was allowed yesterday is allowed today. Instead, it will offer a more precise definition of extremist activity.

“This was a clarification, as opposed to widening the aperture of what would be considered prohibited extremist activity,” said one official.

The guidance does not prohibit specific extremist groups or organizations.

“We were very conscious of not focusing on any particular ideology or any political organization, but focusing exclusively on actions,” said one official.

For years, the Defense Department relied on a nebulous definition of extremist activity that listed it among a wide array of prohibited behavior. A military document, most recently updated in 2012, said service members cannot “actively advocate” extremist ideology or causes, and they must “reject active participation” in such organizations.

But the prohibition on active advocacy and participation left a wide margin of allowable activity and was open to interpretation. For example, service members could be members of extremist organizations, just as long as they didn’t take part in extremist activities. It also offered no clear guidance on an enforcement mechanism or instructions for commanders.

This new guidance aims to fix that.

The officials said they counted approximately 100 cases of extremism within military ranks in 2021, with each of the services having “low double digits.” The total represents an increase, the officials said, but it was unclear whether that was a result of better awareness within the military or the signs of the spread of extremism within the services.

One official noted that the rise of domestic violent extremism across the country may be a warning sign of a potential rise within the Defense Department in the coming years.

Pentagon press secretary John Kirby told reporters on Monday the new guidance “preserves a service member’s right of expression to the extent possible, while also balancing the need for good order and discipline.”

Extremism has been one of the top priorities at the Pentagon since Defense Secretary Lloyd Austin was sworn in, especially after the January 6 riot. At least 74 current or former US military service members have been charged in the attack on the US Capitol, according to CNN’s analysis of Pentagon records and court filings.

In early February, Austin ordered a military-wide pause and review of extremism policies across the services, designed for commanders to talk to their troops about extremism and to get a sense of how widespread extremism is. Austin also instructed the services to improve their screening of new recruits and better train those leaving the military.

Crucially, the Pentagon also sought a sharper definition of extremism and extremist activity.

“The secretary heard from personnel across the force about the need to update and clarify this policy during the standdowns that he directed earlier this year,” Kirby said Monday. “That was one of the common bits of feedback that we got, was that they wanted more clarity. And so we tried to do that with this new instruction.”

For the first time, the new directive also covers social media.

“It basically clarifies that service members are responsible for the contents that they publish on all personal and public internet domains, including social media sites, blogs, and websites,” said one official.

Now, liking or sharing a post that promotes extremist activity could be prohibited.

“Liking something with the intent to promote or endorse would be in violation of the policy,” said one official. “There has to be a knowing element to it, so there has to be an amplification of the message.”

The military won’t actively screen service members’ social media accounts, but if there is an investigation into an extremist incident, social media posts may become part of that investigation, the officials said.

The officials who worked on the final report from the Countering Extremism Working Group were fully aware of the challenge of focusing on extremist activity, which can be prohibited, instead of extremist beliefs, which are constitutionally protected under the First Amendment.

“It’s threading a very fine needle when we’re engaging in prohibiting conduct that may be protected by the First Amendment,” said one official. “There’s always going to be this balancing that goes on.”

This story has been updated with comments from Pentagon press secretary John Kirby on Monday.

CNN’s Michael Conte and Etolia Stinson contribtued to this report.