Facebook has started deploying new weapons in its battle against fake news.

The election of Donald Trump to the presidency of the United States has led to a lot of soul-searching, not least of which by the world’s largest social network. Facebook has been repeatedly accused of facilitating and magnifying an ecosystem of websites that spread false information and conspiracy theories across the platform. That criticism led Facebook to announce late last year that it would be collaborating with “third-party fact checking organizations” to identify stories that don’t hold up to scrutiny, and warn users when they try to post these stories.

The new feature appears to be picking up steam. The Facebook fact-checker has begun flagging a story that was shared widely on the lead-up to St. Patrick’s Day (March 17) that falsely claims thousands of Irish people were brought to the United States as slaves. This is what happens when you try to share the story on Facebook:

Here is me.

Let’s say ”what’s on my mind” is this Newport Buzz article “The Irish slave trade–the slaves that time forgot.” When I paste in the link, Facebook immediately displays a big warning icon in my post’s pop-up window saying this article is disputed by Snopes.com and the Associated Press.

Clicking on that warning produces another pop-up with more information about the dispute. This second pop-up emphasizes that the sources Facebook points to adhere to Poynter’s non-partisan code of fact-checking principles, and it also links me to Facebook’s official help page on disputed content.

From here, Facebook links me to pages on Snopes and AP that fact check the Irish slavery story. (Spoiler: There was no Irish slave trade.) The AP writes, “The false articles, trending on social media as Ireland’s national holiday approaches Friday, typically reprint entire sections from a comprehensively debunked 2008 column posted on a website that promotes conspiracy theories.”

But if I choose to ignore the big warning symbol and go ahead and click “Post,” the story is still not shared immediately. Another pop-up reasserts that this content is “disputed,” and I have to click “Post Anyway” in order to share the link on my timeline.

And if I still click ”Post Anyway,” it doesn’t let me off the hook: Instead, it shows the warning flag below the post in my timeline.

It’s currently unclear how often these disputed articles are being flagged on Facebook to spark the fact-checking pop ups. The feature was announced a few months ago, but this appears to be the first time the internet populace has noticed it in action on a widely shared article. (We have reached out to Facebook to responded to my questions about the frequency and implementation of these pop-ups. We will update this story if and when they do.)

The feature is already being criticized by the kinds of Trump supporters who have disdain for the “mainstream media,” which Trump himself regularly calls “fake news.” Search for “Facebook warning” on Twitter and you’ll find many people either asserting that the Irish slave trade was real or criticizing Snopes.com for being a biased, left-wing outlet. (Conservatives in America have for some time been saying that “fact-checking” has a liberal bias.)

Stopping the spread of false information is a tremendous task for Facebook—there is simply too much content for them to vet manually. So far technological solutions, including using advanced machine learning and natural language processing to verify news, have failed. Facebook’s latest venture appears to be a hybrid human-computer solution, relying on professional fact-checkers for verification and its algorithms for identification of a fake story.

That said, Facebook still allows users to post the debunked Irish slaves link, despite the platform’s insistence that the article is disputed by highly reputable fact-checkers. So while their new methods may lead users to share fewer falsehoods, Facebook may also become further subject to accusations that they are the real purveyor of fake news.