Following Friday's terrorist attacks in Paris, hacktivist group Anonymous declared "cyber war" on ISIS. The accounts were reportedly removed after the group posted the details on Pastebin, along with a message reading:

"Greetings citizens of the world, we are Anonymous,
Operation ISIS Continues:
First we need to clarify few a things.
We Are: Muslims, Christians, Jews...
We Are hackers, crackers, Hacktivist, phishers, agents, spies, or just the guy   from next door.
We Are students, administrators, workers, clerks, unemployed, rich, poor, We are   young, or old, gay or straight.
We wear smart clothes or rugs, we are hedonists,  ascetics, joy riders or  activists.
We come from all races, countries, religions, and ethnicity.
UNITED AS ONE, DIVIDED BY ZERO...
We Are Anonymous.
REMEMBER...THE TERRORISTS THAT ARE CALLING THEMSELVES ISLAMIC STATE,(ISIS), ARE  NOT MUSLIMS!!!.
ISIS; We will hunt you, Take down your sites, Accounts, Emails, and expose you...
From now on, no safe place for you online...
You will be treated like a virus, And we are the cure...
We Own The Internet...
We are Anonymous, We are Legion, We do not forgive, We do not forget, Expect us."

Following the removal, a note purportedly written by ISIS members has made the rounds on Twitter. It's a quick guide to avoiding a doxing.

ISIS idiots instructions to avoid #OpISIS #OpParis fighters. pic.twitter.com/EjNMAnSDNJ

— GhostSecPI (@GhostSecPI) November 16, 2015

While Anonymous' intentions are certainly good, some fear it will eliminate important streams of intelligence. Olivier Laurelli, a French cybersecurity expert, told AFP, “to close those accounts is to leave police deaf and blind around some matters.”