It's even easier. I was carrying a metal external hard drive, put it through the belt with no problem. You could easily take out the HD and put some explosives in there instead.
edit Also, if combining fluids really is a threat, they're allowing liquid medicine bottles, now. It really /is/ theater.
I've had bottles of liquid in my carry on several times by accidents - what happens when you travel alone with a toddler and get slightly frazzled. They've never caught it.
edit Also, if combining fluids really is a threat, they're allowing liquid medicine bottles, now. It really /is/ theater.