Reddit, the online internet forum, has started to implement a new policy to ban content that glorifies and incites violence, and among the first to go were forums for Nazi, racist and white supremacist groups.

The company outlined the update to its policy Wednesday, with one statement in its help center and another by an administrator on the site itself, where vocal users challenged the changes.

Reddit said it was taking the steps to clarify the way it has moderated posts in the past, and to bring its policy on allowable content in line with its values.

“In particular, we found that the policy regarding ‘inciting’ violence was too vague,” the statement said.

“Going forward, we will take action against any content that encourages, glorifies, incites, or calls for violence or physical harm against an individual or a group of people; likewise, we will also take action against content that glorifies or encourages the abuse of animals.

“We understand that enforcing this policy may often require subjective judgment, so all of the usual caveats apply with regard to content that is newsworthy, artistic, educational, satirical, etc, as mentioned in the policy. Context is key.”

Reddit said the updated policy would apply to memes, CSS/community styling, flair, subreddit names and usernames. If the content is “borderline,” it should be tagged with a warning.

“Even mild violence can be difficult for someone to explain to others if they open it unexpectedly,” the statement said.

But it added sometimes there were reasons to post violent content — such as with educational, newsworthy, artistic and satirical items — in which case context should be provided to show it was not gratuitous.

On Thursday, as news of the policy surged through the site, moderators began to question how it would be applied in Reddit’s micro-communities, or subreddits, where interests can range from hunting to Bible study, as well as in its dark corners, where people are urged to kill themselves or others.

“What does glorify mean?” one wrote. “Will subs like ‘watchpeopledie’ be categorized as such?” (That forum would remain for now, a moderator said.)

Among the first to be banned were the subreddits r/NationalSocialism, r/Nazi and r/Far—Right.

In a statement Thursday, Anna Soellner, a spokeswoman for Reddit, said the company was constantly assessing its content policy.

“We strive to be a welcoming, open platform for all by trusting our users to maintain an environment that cultivates genuine conversation,” she said.

Reddit was founded in 2005 and has some 330 million monthly active users.