Anonymous says to ISIS: 'War is unleashed'

The hacking group Anonymous redoubled its cyberwar against the Islamic State (IS) "to defend our values and our freedom" after Friday's terrorist attacks in Paris, which killed 129 civilians as they enjoyed a soccer match, dinner at a café or a rock concert.

A number of videos from Anonymous-affiliated accounts appeared online this weekend in French, Italian, and English, with presenters wearing the hacking collective's signature Guy Fawkes mask.

"We are going to launch the most important operation ever carried out against you," a robed figure warns in one video, as news footage of the attacks plays in the background. "War is unleashed. Prepare yourselves."

The declaration was repeated on hackers' Twitter accounts, such as @GroupAnon. 

At 11 p.m. Sunday evening, the group revealed their first targets: a list of nearly 1000 Twitter accounts it claims are affiliated with Islamic State.

Due to the size of the list, publications have found it difficult to verify all of the accounts' activity.

The hackers' usual slogan — "We Are Anonymous, We Do Not Forgive, We Do Not Forget, Expect Us!" — is directed at Islamic State in multiple videos, Tweets, and the "dox" list, a term for revealing Web users' identities. 

IS first drew Anonymous's ire in August 2014, when they declared war, but the hackers' first major victory came in the wake of another Paris attack, the January 2015 massacres at satirical magazine Charlie Hebdo's offices and at a kosher grocery store. Al Qaeda claimed responsibility for three days of violence, which killed 20 people.

Teaming up with hacker groups GhostSec and Ctrlsec, Anonymous managed to reveal 9,200 IS-linked social media accounts in March, with an Anonymous source called the "hub" of IS's online activity, after shutting down a French extremist website within days of the attacks. 

Anonymous has long attracted controversy for members' brash virtual vigilantism and sometimes inaccurate identifications, which critics allege can put innocent Web users in danger. But their threats to IS may pose special difficulties, or opportunities, for the hackers themselves and the United States government.

The Islamic State's sprawling Web presence has been a major asset for the militant group, with each new violent video attracting international condemnation, but also drawing fresh recruits — a 21st century challenge the US has seemed unsure how to tackle, apart from the Department of State's "Think Again Turn Away" campaign meant to rebut extremist arguments. 

Part of the difficulty is in constantly re-assessing the evolving rules and techniques of cyberwar, but in addition, simply shutting down sites isn't necessarily in the government's best interest. Members and recruits can be tracked through their online activity. 

OpParis, as Anonymous' new initiative is called, aims to focus on stealing sites' information rather than relying on site shut-downs alone, according to the International Business Times. 

E. T. Brooking, a defense researcher at the Council on Foreign Relations, has suggested that the US harness Anonymous's strengths to fight a virtual war, overcoming their "traditionally antagonistic relationship" to force IS "into deeper and deeper parts of the web."

Mr. Brooking questions the government's focus on countering IS claims, rather than destroying sites and accounts themselves.

"As anyone who’s ever gotten in a political debate on Twitter can tell you, the availability of a viable counter-narrative in no way guarantees that somebody will actually listen to it," he wrote for Foreign Policy in March.