The U.S. military has reportedly banned all removable media from use on classified systems. It's not that I disagree with the policy as much as I wonder why they waited so long and how well they can enforce it.
Many years ago when I was in the Air Force, they had a Two Man Rule which I'm sure they continue today. Areas where people had access to nuclear weapons, or nuclear weapon control systems, were designated as No Lone Zones. The idea was that if one person tried to do something unauthorized, the other could stop them or call for help.
First of all, systems containing classified information are in restricted areas--as long as things haven't changed since I got out in '98. I understand military ID cards are actually Smart Cards used for logging on to systems nowadays, too. But even so, with as many computers the military has it seems they almost have to designate each one as a No Lone Zone if they truly want to ensure nobody uses removable media around them. After all, it's not like you can easily identify all removable media. You can fashion one to hide inside a wall jack, buy a watch, a credit card, a pen, and even have them made inside a toy or knick knacks.
And then there's the human factor where someone is allowed to do something "just this one time".
Nobody wants to be the first person prosecuted for violating this order. They will be made a public example and the consequences will be severe in order to instill fear of those consequences in everyone else.