See http://www.bbc.co.uk/news/world-us-canada-30785232 .
IS has hacked the Twitter account of the US Central Command and the Twitter account has been taken down. I don't know the full details, but you would expect better security from these people. A wake-up call certainly. As the BBC say they did not hack into the most secret parts, but no doubt extra layers of security will now be added. Cyber crime is now a real war-ground in the 21st century.