See this blog post for some investigation into the issue. Story doesn't hold up in my opinion though - if international credit card usage was such a small percentage then they should have been able to manage the fraud. points.com has no problems with other airline programs with international cards.
Perhaps someone with the ear of Alaska Airlines could suggest in the meantime that they allow international wire transfers to buy miles by Australians.
Alaska Airlines freezes out Aussie frequent flyers in credit card fraud crackdown - Flights | hotels | frequent flyer | business class - Australian Business Traveller
Dale.
It has little to do with fraud.
The reason for the change in policy is that AS want to offer buying miles promotions to AS FFers who actually fly AS, not Australian customers who will never set foot on an AS plane and will use it purely to book award seats with partner airlines. They clearly do not make nearly as much money selling partner award seats as they do selling seats on their own metal. US Airways never thought of this.