An ISIS flag is seen in this illustration from February 18, 2016.
"This will cause the most almighty blow to IS's operations."
That's how Will Geddes, security expert and founder of Corporate Security Services in the UK, describes the release of a trove of documents that belonged to ISIS.
A former member of the terrorist group stole memory sticks that belonged to the head of ISIS's internal security police. The ISIS member, who calls himself Abu Hamed, had joined the extremist group, but later defected.
He handed the documents over to German media outlets and spoke with Britain's Sky News.
The documents contain personal data on at least 22,000 ISIS recruits. Among them are recruitment forms that ask for names, addresses, phone numbers and family contacts.
Geddes says intelligence agencies are trying to verify the authenticity of the documents. He believes there is a strong possbility they are real.
The next step will be to sift through them and use the data to counter ISIS' efforts.
"Some of the identifiers in these documents are going to be essential in terms of not only naming specific individuals, but also naming some of their referrals or recruiters," says Geddes.
He adds that the intelligence community will also be looking to identify those recruits who have agreed to become martyrs and carry out suicide missions. "It's not necessarily going to tell us exactly where the next possible attack will take place, but what it will do is potentially show what players are in which particular regions and which particular countries," Geddes says.
Coupled with information the intelligence agencies already have, these documents could help create a more clear picture of the inner workings of ISIS and potential future threats. Geddes believes it's highly likely that the German and British intelligence agencies will share the data with allied countries.
"Because there is a good joined operation these days between multi-national agencies, there is a very good chance that duplication of this data will be provided to our counterparts in the United States and into various various other agencies around the world," he says.