How do you solve a problem like 8chan?

President Donald Trump’s vow to scour “the dark recesses of the internet” came as deadly gun violence provoked ire over fringe online platforms like 8chan, an anonymous message board that has hosted a racist manifesto linked to Aug 3's deadly shooting in El Paso (TX). But any effort to curb dangerous extremism online will run into a host of obstacles:

1. US law offers a safe harbor: The First Amendment protects even racist, misogynistic, and other hateful speech. And online sites enjoy broad legal immunity through another statute — Section 230 of the 1996 Communications Decency Act — that has become a major focus of the bipartisan congressional backlash against online sites like Facebook.
2. Fringe sites often escape scrutiny: The fringe quality means it's harder to get such sites to remove content than it was to get big social media companies to remove videos and posts by Islamic State supporters.
3. Even the big sites still provide gateways to radicalism.
4. Racially divisive speech can fail to trigger the necessary alarms, as Washington fails to treat white supremacy as a serious threat. 
5. The real decision-makers — internet infrastructure companies — don’t want the responsibility: The real power brokers at the moment are the internet infrastructure companies that have the power to erase whole sites from the web, at least for a time. But they don't want to take on the responsibility of determining what content is good or bad.