Just a comment after our recent holiday. Travelling from America on international flights check-in luggage must be left unlocked. Locked luggage is not accepted. Just presenting a locked bag is viewed as suspicious. Your check-in luggage can be examined at any point.

In Australia the rules are different and check-in luggage is examined while you are present - if you are selected for this. We only took what we could carry on board and bought what we needed in America. Joy