Much of the attention paid to Russian interference in American politics has focused on the Trump campaign. This ignores that the Kremlin is an equal opportunity offender exploiting all divisions in our society and creates a dangerous blind spot in the fight to thwart foreign meddling.

Just look at Aztlan Warriors, Black Elevation, and Resisters. Facebook has blocked these groups for using “coordinated inauthentic behavior” to influence our politics. Aztlan Warriors played on the fantasist wish of radical Chicano activists who want to split portions of the southwest from the rest of the country. Black Elevation was meant to appeal to African Americans. Resisters sought to attract to feminists. Moreover, the Verge reported that Facebook also “found suspicious accounts engaging in coordinated activity around the #AbolishICE movement.”

Clearly, Moscow is trying to infiltrate both left and right, just as it did in the Cold War era. Soviet agents both recruited radical black activists and impersonated Ku Klux Klan members to stoke racial hatred. Russia certainly understands how identity politics have divided our nation along lines of ethnicity, race and sex. Clearly, Moscow is trying to exploit and aggravate these divisions to sow disorder and destabilize America.

The Trump administration is taking the Russian operation seriously. It appears that Facebook is too, as it has briefed congressmen on the issue. A spokesman for Senate Judiciary Chairman Chuck Grassley (R-Iowa) toldFox News that Facebook had informed the his office that a “limited group of Russian actors has attempted to spread disinformation using its platform and that the affected groups are affiliated with the political left.”

Here is an example of how these bad actors work. The Resisters group tried to instigate a potentially violent confrontation at the “Unite the Right” rally of white supremacists slated for this weekend in Washington by creating a counterprotest event on Facebook. It enlisted the support of real people and got five legitimate pages to support the event.

According to TechCrunch, the Facebook event was embraced and “taken over by a handful of real DC area activist groups, including Smash Racism DC, Black Lives Matter DC, Black Lives Matter Charlottesville, and other local groups.” None of them knew the true origins of the event. When Facebook announced why it was blocking Resisters, a spokesperson for one of the legitimate activist groups bemoaned that action as “really outrageous for us,” adding that makes them look like “Russian pawns.”

Aztlan Warriors, Black Elevation, and Resisters were among the 32 fake pages that Facebook blocked last week. Along with Mindful Being, these four pages accounted for the vast majority of the total 290,000 followers of the fake pages. The other 28 pages had only 10 or fewer followers each. From more than a year, they paid Facebook some $11,000 in American and Canadian dollars to run about 150 ads. While Facebook was careful not to identify any nation state definitively as the culprit, it did find sufficient evidence linking at least one of the accounts to Russia.

As Facebook put it, bad international actors have grown increasingly sophisticated online, and they are getting a lot better at hiding their connection to social media accounts that seek to exploit polarizing divisions. Facebook said that it is “clear that whoever set up these accounts went to much greater lengths to obscure their true identities” than the Internet Research Agency based in Russia has done in the past.

So Facebook had to wait for the bad actors to slip up. In this case, that mistake lasted just seven minutes, which was enough for Facebook to act. Facebook, like Twitter and Google, is trying to thread a very difficult needle. From Boston to Bangladesh, social media have contributed enormously to the pursuit of happiness. As we have seen, however, bad actors can and do abuse social media to subvert societies, especially open ones. Russia is but the tip of the iceberg. China is a worse offender.

The problem is that Silicon Valley has aimed its fire more on conservative ideas. Recently, for example, Facebook blocked ads for an academic book by the Israeli philosopher Yoram Hazony on spurious grounds. Perhaps the technology giants are not biased. Perhaps, as David French wrote, this is because they base their decisions on the extraordinarily vague and subjective notion of hate speech, instead of more durable and accepted concept of slander. But as Russia has shown, social media is vulnerable to destabilization from the right and the left, just like the United States itself.