Thank you for all your informative responses. Before making my first post, I had already decided that I'll never spend my own money to fly Northwest anymore. The only responses I'd concur are i.) it's useless to be a Worldperks silver and ii.) I shouldn't let this misery began in the first place by flying NWA. I paid NWA for the ticket, checked an unlocked luggage and got it back damaged.

This is a Northwest forum, so maybe most of you are accustomed to inspect your luggage when transiting at DTW/MSP/MEM after an international flight. I do not, especially when you had to fight to get your bags with 400+ people (from a 744, at least that's my case) along the baggage carousel and had to rush for the connecting flight to ORD.

I guess this is a loss that I have to take this time with NWA. But this will also be the last time. NWA simply can’t get my luggage home in one piece. TSA don’t care who locked the luggage. If it’s locked, they’ll break it. Flying non-stop to my home airport will make sure no one from TSA will touch my bags after I enter the U.S. and clear customs. For all my future travels to HKG and other places around the world, I will only select non-stop flights. I have no bias against NWA, but whenever a transit is required for an international flight, be prepared for damages on your luggage.