Online “hacktivist” group Anonymous claimed Sunday it had stolen a trove of emails and credit card information from US-based security firm Stratfor’s clients, and vowed additional attacks.

Hackers provided a link on Twitter to what they said was Stratfor’s private client list, which included the US Defense Department, Army, Air Force, law enforcement agencies, top security contractors and technology firms like Apple and Microsoft.

They also posted images online claiming to show receipts from donations made by the hackers on behalf of some of Stratfor’s clients by using their credit card data.

“Anonymous hacks and discredits @STRATFOR intelligence company,” Twitter user YourAnonNews wrote on the micro-blogging website. “Maybe they should learn what encryption is.”