why won't apple accept US Bank credit cards for accounts with Canadian addresses

QUESTION: Why is Apple ID Account for iTunes and Store Method of Payment is said to be, "not valid in this Store".

Method of payment is a bank credit card in Canada with my home address in Canada and has been a working method of payment until today.

My bank does not have a block or other hold on the account and Apple charges have been previously charged to this credit card.

There is no bank issue and there is plenty of funds in the account without any pending charges.