Goods shall be considered as directly shipped to the United States from Canada for the purpose of eligibility for preferences under the Agreement only under the following circumstances:

(a) Through shipment. The goods have been shipped directly from Canada to the United States without passage through the territory of any third country; or

(b) Shipment through a third country. The goods were shipped through the territory of a third country but:

(1) The goods did not enter the commerce of any third country;

(2) The goods did not undergo any operation other than unloading, reloading, or any operation necessary to transport them to the United States or to preserve them in good condition; and

(3) All shipping and export documents show the United States as the final destination.