Activists of the international network "Anonymous" behind their masks posing in Berlin.
Activists of the international network "Anonymous" behind their masks posing in Berlin.

The “Islamic Cyber Army," the Islamic State’s cyber arm, has responded to Anonymous’ declaration of “total war” by calling the shadowy hacking group “idiots.”

On Monday, Anonymous said it would unleash the “biggest operation ever” against the Islamic militant group as a response to the Paris massacre that left 129 dead.

In addition to name calling, IS issued guidance via the Telegram privacy app to its supporters to protect themselves from cyber attacks.

“The Anonymous hackers threatened in new video release that they will carry out a major hack operation on the Islamic State (idiots),” read the IS statement. “What they gonna hack...all they can do is hacking twitter accounts, emails etc…”

The statement reminded IS supporters not to open suspicious links, and to take other precautions to avoid being hacked.

“Do not talk to to people u don’t know on telegram and block them if u have to cause there are many glitches in telegram and they can hack you by it. Don’t talk to people on twitter DM cause they can hack u too,” read the statement. “Do not make your email same as your username on twitter this mistake cost many Ansar (helpers) their accounts and the kuffar published their IP so be careful.”

Anonymous posted an unverified video on YouTube on Monday, saying it could not let the Paris attacks go unpunished.

The Anonymous spokesman said it would be the group's biggest operation, "Expect many cyberattacks. War has been declared. Get ready," the man said, without giving details of what the attacks would involve. "We do not forgive and we do not forget."

Since the attack on French weekly Charlie Hebdo last January, which led to the deaths of 17 people, Anonymous activists have waged an online vigilante campaign to force the shutdown of Twitter profiles suspected of belonging to IS supporters.

The group says it has identified more than 39,000 suspected IS profiles and reported them to Twitter. It claims to have had more than 25,000 of these accounts suspended. Nearly 14,000 more on the targeted list remain active, according to a list posted to a site calling itself Lucky Troll Club.