The Internet Research Agency is a Russian troll farm in St. Petersburg—in essence a Kremlin-backed enterprise staffed with hundreds of people whose main job is to sow disinformation on the internet. The organization, which serves as a propaganda arm for Russian President Vladimir Putin, is at the heart of the indictments handed down Friday by Special Counsel Robert Mueller.

The indictment alleges that IRA officials began targeting the United States in 2014 and continued until the November 2016 election that saw the election of President Trump. (The indictment does not allege collusion between these individuals and the Trump campaign.) The IRA, which is based in St. Petersburg, is funded by Evgeny Prigozhin, a Russian oligarch who is close to the Kremlin. He was among 13 people indicted Friday.

The troll farm’s operations began inside Russia after massive anti-government protests against Putin in 2011. In those demonstrations, the Russian opposition successfully harnessed social media to help drive protesters out into the streets. As Adrian Chen wrote in The New York Times Magazine in 2015, Vyascheslav Volodi, the architect of Putin’s domestic policy, came into office in 2012. His job was to rein in the internet. (He was not indicted Friday.)

The battle was conducted on multiple fronts. Laws were passed requiring bloggers to register with the state. A blacklist allowed the government to censor websites without a court order. Internet platforms like Yandex were subjected to political pressure, while others, like VKontakte, were brought under the control of Kremlin allies. Putin gave ideological cover to the crackdown by calling the entire Internet a “C.I.A. project,” one that Russia needed to be protected from. Restrictions online were paired with a new wave of digital propaganda. The government consulted with the same public relations firms that worked with major corporate brands on social-media strategy. It began paying fashion and fitness bloggers to place pro-Kremlin material among innocuous posts about shoes and diets...

As Putin and his allies took greater control of the Russian internet, opposition voices began getting drowned out online. Russian media reports say the IRA was functioning by the summer of 2013. By the following year, Friday’s indictment points out, the IRA was targeting the U.S.