A hacker group calling itself the Russian branch of Anonymous has claimed responsibility for shutting down the websites of the Kremlin and the Russian President.

The sites kremlin.ru and президент.рф have been unavailable for almost an hour on Wednesday.

Anonymous tweeted “Kremlin.ru – TANGO DOWN” on their Twitter account, co-opting the military-derived code word to report their successful attack. They also provided screenshots, demonstrating that the site was unavailable in different countries around the world.

The website of the Russian Federal Security Service, fsb.ru, has also had performance problems throughout the day, although there is no information on whether it has anything to do with Anonymous.