Anonymous Launches Month-Long Hacking Campaign Against Banks by Don Reisinger @FortuneMagazine May 4, 2016, 12:57 PM EDT E-mail Tweet Facebook Linkedin Share icons The hacking collective Anonymous has already launched one successful campaign against banks and has more planned. Members of the secretive collective on Tuesday successfully hacked the Bank of Greece, an unidentified official at the bank told Reuters. According to the official, the hackers were able to take down the Bank of Greece website, but it only “lasted for a few minutes.” The bank’s security systems prevented any data leaks, the official told Reuters. Still, it was an ominous threat that could have an impact on banks across the world. Indeed, an apparent Anonymous member said in a video posted to YouTube that members of the hacking collective have decided to attack “central bank sites across the world.” While the video didn’t say which bank websites would be attacked, it was noted that the campaign would last 30 days. Anonymous is one of the most well-known hacking collectives in the world. The collective has no structured organization and members participate in different operations whenever they like. The group has targeted a wide range of organizations, companies, and individuals over the years, including Presidential candidate Donald Trump, Wall Street, and others. Get Data Sheet, Fortune’s technology newsletter In the YouTube video, Anonymous said that its attack on banks is an extension of Operation Icarus, a campaign the collective previously launched against Wall Street. It’s now bringing it back over the next month. While the video failed to explain exactly why Anonymous members are deciding to attack central banks around the world, the group said that there is a “global banking cartel” that is capitalizing on the hard work of others. “This is a call to arms, brothers, who for too long have stood for nothing but have criticized everything,” Anonymous says in the video. “Stand now, behind the banner of free men against the tyrannical matrix of institutions that oppose us. Take your weapons and aim them at the Global Banking Cartel. This is the operation to end all others. In the beginning some people may stand to lose something from this, but the powers that be stand to lose much more. Bring the rain, brothers!” The video ends with an ominous threat: “Global Banking Cartel, you’ve probably expected us.” For more about Anonymous, watch: It’s unknown whether Anonymous members have targeted other banks around the world or which organizations could be targeted. It’s also unknown how many members will participate in the campaign. But banks around the world might want to ensure they’ve fortified their defenses.