WASHINGTON — Warning that extremism in the ranks is increasing, Pentagon officials are issuing detailed new rules prohibiting service members from actively engaging in extremist activities. The new guidelines come nearly a year after some current and former service members participated in the riot at the U.S. Capitol, triggering a broad department review.

Senior defense officials tell The Associated Press that fewer than 100 military members are known to have been involved in substantiated cases of extremist activity in the past year, but they warn that the number may grow given recent spikes in domestic violent extremism, particularly among veterans.

Officials said the new policy doesn't largely change what is prohibited, but is more of an effort to make sure troops are clear on what they can and can't do, while still protecting their First Amendment free speech rights. And for the first time, it is far more specific about social media.

The new policy lays out in detail the banned activities, which range from advocating terrorism or supporting the overthrow of the government to fundraising or rallying on behalf of an extremist group or “liking” or reposting extremist views on social media. The rules also specify that commanders must determine two things in order for someone to be held accountable: that the action was an extremist activity, as defined in the rules, and that the service member “actively participated” in that prohibited activity.

Previous policies banned extremist activities but didn't go into such great detail, and also did not specify the two step process to determine someone accountable.

What was wrong yesterday is still wrong today, said one senior defense official. But several officials said that as a study group spoke with service members this year they found that many wanted clearer definitions of what was not allowed. The officials spoke about the new rules on condition of anonymity because they have not yet been made public.

The military has long been aware of small numbers of white supremacists and other extremists among the troops. But Defense Secretary Lloyd Austin and other leaders launched a broader campaign to root out extremism in the force after it became clear that military veterans and some current service members were present at the Jan. 6 insurrection.

The risk of extremism in the military can be more dangerous because many service members have access to classified information about sensitive military operations or other national security information that could help adversaries. And extremist groups routinely recruit former and current service members because of their familiarity with weapons and combat tactics.