We now know Russia isn't the only foe that's learned to exploit U.S. social media

Silicon Valley’s biggest social media companies provide some of the best tools for spreading propaganda. Social media poses an ongoing risk that will only grow without a coordinated effort to prevent manipulation. “The main takeaway from Facebook's announcement is not just that Russia-style meddling is exportable, but that it's inevitable,” said Chris Meserole, a fellow in the Center for Middle East Policy at the Brookings Institution. “If Moscow authored the playbook, Tehran read it word for word, and they won't be the only country to do so. Spreading disinformation on Facebook is so easy and effective that we need to assume every foreign adversary will now do it.”