My experience, with lots of international travel, is that they already open your bag. And if I locked the bag? They just snipped off the zipper. I'm a softie- never did try to get them to pay for the damage to my bags. So now? I use string - to keep the zipper from accidentally opening, and to keep them from damaging the bag if they want to cut the string and open it. I've never had anything stolen from the bag, thankfully.