After the Paris terror attacks on Friday that left at least 129 people dead and hundreds more injured, the hacking collective posted a video in which a person who claims to represent the group said, “Anonymous from all over the world will hunt you down. We will launch the biggest operation ever against you. Expect massive cyberattacks. War is declared. Get prepared.”

While Anonymous was not specific in their threat, there has already been much speculation about what they could do to ISIS. One possibility includes the idea that they might hack into ISIS’ private networks and release vital military information such as battle plans, or even the names and personal information of those involved in ISIS’ terrorist activity.

You can watch the whole video from Anonymous here:

ISIS response to Anonymous Group:

ISIS has been quick to respond to the warning from Anonymous. An ISIS-affiliated Telegram channel has sent out a message to its followers, giving them instructions on how to avoid getting hacked by Anonymous, calling the group “idiots” in the process.

“The #Anonymous hackers threatened in new video release that they will carry out a major hack operation on the Islamic state (idiots),” the statement read in part.

ISIS gives basic instructions to their followers, such as to never open links if they are uncertain of the source, change their Internet Protocol addresses constantly, and to not talk to people that they don’t actually know on Telegram or through Twitter’s direct messaging system. The message was then forwarded around to various other ISIS-affiliated Telegram channels.