Hacker collective Anonymous has declared "war is unleashed" against ISIS, the Islamic militant group that claimed responsibility for the deadly attacks that occurred Friday in Paris.

ISIS has used the Internet to recruit new members from around the world and to spread chilling images of executions and other violence.

Anonymous, a loosely affiliated group of Internet users who hack and spread leaked information, said in a series of tweets and a YouTube video that it wants to steal information from that Web traffic and force ISIS into Internet obscurity. Indeed, its #OpParis campaign aims to strip ISIS of one of its most valuable tools: the Internet.

In the YouTube video published Sunday, a masked announcer speaks in French. The statement was widely translated as saying, "Expect massive cyber attacks. War is declared. Get prepared."

Anonymous has leveled its ire at a huge variety of individuals, groups and companies that it perceives as crossing ethical and moral lines. Their attacks involve leaking documents and taking down websites with a form of attack called distributed denial of service, which overwhelms websites with too many requests. The group's targets have included the Ku Klux Klan, the Westboro Baptist Church (known for protesting the funerals of fallen soldiers and others in the United States), Monsanto and Koch Industries.

The list of Anonymous' targets also includes governments, such as Tunisia in 2011, in response to reports of censorship during the Arab Spring uprisings.

But ISIS, or the Islamic State in Iraq and Syria, which has been a warring force in the Middle East, just struck at the heart of the Western World.

Anonymous' announcement isn't brand new. It began targeting ISIS earlier, especially after gunmen opened fire at the offices of French satirical magazine Charlie Hebdo in January, killing 12.

#OpParis is aimed at ISIS' use of social media and other Web services. Beheadings and other executions of journalists, members of different Islamic groups and people accused of being gay have circulated on the Web over the past two years. Also, recruitment websites have urged people from around the world to leave their homes and fight with ISIS.

This activity has already gotten the attention of Western governments. For example, law enforcement and intelligence officers monitor recruitment websites. Anonymous seems fixed on amplifying these efforts with its brand of crowdsourced hacking, nevermind the law.

On Monday, a Twitter handle calling itself the official #OpParis account claimed a number of "pro-ISIS" accounts had been taken down.

Anonymous, however, isn't a unified group, and dissenters were tweeting their disapproval on Monday. One Anonymous-affiliated Twitter user, who goes by the handle Discordian and claims to have participated in several Anonymous hacking efforts, said he opposes #OpParis for a variety of reasons.

"[H]ow exactly do they plan to stop an international terrorist organization that has been able to plot attacks regardless of the mass-spying by governments around the globe?" Discordian wrote on a text-hosting website called Pastebin.

Predictions from those in the cybersecurity industry of whether Anonymous will be successful are mixed, with experts saying they understand why Anonymous wants to target ISIS.

Stu Sjouwerman, founder and CEO of cybersecurity company KnowBe4, is optimistic that Anonymous will be successful. "I wish Anonymous good luck with this campaign," he said.