The Twitter account for U.S. Central Command was apparently hacked on Monday, with pro-ISIS messages plastering the account's profile.

The first message was posted at 12:29 p.m. ET, with the words "AMERICAN SOLDIERS, WE ARE COMING, WATCH YOUR BACK. ISIS." and the hashtag "#CyberCaliphate."
http://www.cnbc.com/id/102330338#.