I don't think that there are any problems with flights originating outside the US, even if they're going to the US. Locks have always been acceptable and indeed recommended by airlines.
It's only for US-originating flights, where the TSA is responsible for screening, that the TSA recommends that you don't lock your bags because they may want to smash their way inside them if you do.
.......It was a flight
to the USA originating at Gatwick (CO 5) and terminating in Houston when the TSA destroyed my bag!!!