Twitter’s controversial “Hide Replies” feature, aimed at civilizing conversations on its platform, is launching today in the U.S. and Japan after earlier tests in Canada. The addition is one of the more radical changes to Twitter to date. It puts people back in control of a conversation they’ve started by giving them the ability to hide those contributions they think are unworthy.

These replies, which may range from the irrelevant to the outright offensive, aren’t actually deleted from Twitter. They’re just put behind an extra click.

That means people who come into a conversation to cause drama, make inappropriate remarks or bully and abuse others won’t have their voices heard by the majority of the conversation’s participants. Only those who choose to view the hidden replies will see those posts.

Other social media platforms don’t give so much power to commenters to disrupt conversations. On Facebook and Instagram, for example, you can delete any replies to your own posts.

But Twitter has a different vibe. It’s meant to be a public town square, where everyone has a right to speak (within reason.)

Unfortunately, Twitter’s open nature also led to bullying and abuse. Before today, the only options Twitter offered were to mute, block and report users. Blocking and muting, however, only impact your own Twitter experience. You may no longer see posts from those users, but others still could. Reporting a tweet is also a complicated process that takes time. It’s not an immediate solution for a conversation rapidly spinning out of control.

While “Hide Replies” will help address these problems, it ships with challenges of its own, too. It could be used as a way to silence dissenting opinions, including those expressed thoughtfully, or even fact-checked clarifications.

Twitter believes the feature will ultimately encourage people to better behave when posting to its platform.

“We already see people trying to keep their conversations healthy by using block, mute, and report, but these tools don’t always address the issue. Block and mute only change the experience of the blocker, and report only works for the content that violates our policies,” explained Twitter’s PM of Health Michelle Yasmeen Haq earlier this year.

Since launching in Canada in July, Twitter said that people mostly used the feature to hide replies they found were irrelevant, abusive or unintelligible. User feedback was positive, as well, as those who used the tool said they found it was a helpful way to control what they saw, similar to keyword muting.

In a survey, 27% of those who had their tweets hidden said they would reconsider how they interact with others in the future, Twitter said. That’s not a large majority, but it’s enough to make a dent. However, it’s unclear how representative this survey was. Twitter declined to say how many people used the feature or how many were surveyed about its impacts.

The system will now also ask users who hide replies if they also want to block the account, as a means of clarifying that “hiding” is a different function.

“These are positive and heartening results: the feature helped people have better conversations, and was a useful tool against replies that deterred from the person’s original intent,” explained Twitter in a blog post, shared today. “We’re interested to see if these trends continue, and if new ones emerge, as we expand our test to Japan and the U.S. People in these markets use Twitter in many unique ways, and we’re excited to see how they might use this new tool,” the post read.

Despite the expansion, Twitter says “Hide Replies” is still considered a test as the company is continuing to evaluate the system, and it’s not available to Twitter’s global user base.

The new feature will start rolling out at 2 PM PT in both the U.S. and Japan and will be available across mobile and web clients.