Twitter is cracking down on hate speech and not just by looking at its own site.

In what amounts to a major shift in Twitter policy, the company announced on Friday that it will be monitoring user's behavior "on and off the platform" and will suspend a user's account if they affiliate with violent organizations, according to an update to Twitter's Help Center on Friday.

"You also may not affiliate with organizations that — whether by their own statements or activity both on and off the platform — use or promote violence against civilians to further their causes," the update reads.

Twitter isn't taking action immediately. Rather, it's given users until December 18, 2017 when it will then begin enforcing the rule. The month-long wait is due to regulations in the European Union that require companies to inform users of a new policy change 30 days prior to enforcement.

The Dec. 18 deadline also applies to using "hateful images or symbols" in profile images or profile headers. Twitter will also monitor for hate speech in usernames, display names, and profile bios.

This new rule closes a loophole that Twitter's critics had long pointed out: That known white supremacists and others affiliated with hate groups could still use the platform to send a sanitized version of their message and use their followers to bolster their overall profile.

We’ve updated our rules around abuse and hateful conduct as well as violence and physical harm. These changes will be enforced starting December 18. Read our updated rules here: https://t.co/NGVT3qGFvg — Twitter Safety (@TwitterSafety) November 17, 2017

It's unclear how exactly Twitter will prioritize taking action and how much will come from user reports versus its own monitoring.

"The updates to the rules today will be enforced starting December 18. We'll also have more details on these policies to share that day," a Twitter spokesperson wrote in an emailed statement.

These changes comes amid aggressive moves by Twitter to curb abuse and harassment on the site after more than a decade of essentially letting the abusers operate freely.

Over the last week, Twitter has taken action against the accounts of white supremacists. Twitter permanently banned Tim "Treadstone" Gionet, a prominent alt-right troll more widely known as Baked Alaska, earlier this week. It also removed the verification badges of Jason Kessler, one of the organizers of the racist Unite the Right rally in Charlottesville, and of alt-right activist Richard Spencer.

Twitter's decision to monitor users off site sparked concern from free speech advocates such as Andrew Torba, founder of social network Gab. "This is a scary precedent to set," he wrote in an email to Mashable. "Rules like this will only force dissidents and those who are speaking truth to power to silence themselves or risk being silenced by Twitter."