I have travelled various places around the world, and have used cable ties, small, larger padlocks etc. but none of them will deter the detemined
thief, so always keep your valubles in your hand luggage.
I now always use, I think they are called TSA locks, it keeps the zips locked and if officials want to open your bag, they can do without breaking
the lock or zip, they have a special key.
America seems a the most paranoid country as each time I have travelled there they have opened my case and left their leaflet, but the TSA locks are put back undamaged and doing their job, which really is just to keep the zips closed.
I am booked on the October China tour, seems to be still a long time off but my count down on my phone says otherwise.