They use screen aliases like IS Hunting Club, TouchMyTweets and The Doctor. They troll Twitter for suspected accounts of Islamic State fighters, recruiters and fund-raisers. Then they pounce.

In what has become a cyber analogy to the battles in Syria, Iraq and elsewhere between governments and the Islamic State, online vigilantes, some of them with diverse agendas, have united in a common cause to subvert the militant group’s aggressive use of social media, particularly Twitter.

They expose suspect accounts that they post on blacklists via Twitter, and encourage other Twitter users to report the accounts to the social media network’s violations department, a prerequisite for suspension or deletion.

“Basically our work not only cripples their ability to spread propaganda, but also wastes their time,” said a Twitter vigilante who goes by the screen name The Doctor.