How can you prevent this? To start with you can avoid zippered luggage. The argument here would be that the vast majority of suitcases out there are closed using zippers. You can buy TSA-approved locks and slap them on for security. But no matter what locks you put on your zipper tabs, a thief can open zipped luggage in seconds using nothing but a standard office pen. They can also reseal your bag in such a way that you’d never know that it was opened. Here’s a video demonstrating just how easy it is.
If you do still have to use your zippered luggage, you can protect it using tell-tags (Another tamper-evident luggage seal option is Securoseal). Although it’s still possible to open the bags using the pen trick, but it cannot be resealed without destroying the tell-tag, providing evidence that your luggage was tampered with. Of course, don’t forget to seal any secondary compartments or pockets on your suitcase in addition to the main zippered section.
Ultimately the best way to keep your luggage secure is to use hard-sided zipper-less luggage that seals with a built-in lock. A determined thief might still be able to pick the lock, but more than likely, they’ll simply move on to an easier target. Security agents still need to be able to open your bag, so you should check that the bag’s built-in lock is TSA-friendly – which will generally be the case if the suitcase was manufactured within the last few years.