9903.85.71 - Aluminum articles of Mexico enumerated in U.S. note 19 to this subchapter, containing primary aluminum for which the primary country of smelt, secondary country of smelt, or country of most recent cast, is China, Russia, Belarus or Iran

This HTS category, 9903.85.71, specifically addresses aluminum articles originating from Mexico that are subject to additional import restrictions. The defining characteristic for classification under this provision is that the primary aluminum content of these articles must trace its origin for smelting or casting to China, Russia, Belarus, or Iran. This means that even if the final article is manufactured in Mexico, its underlying aluminum's point of origin for critical processing stages dictates its classification here.

This provision is a temporary modification and stands apart from the general trade classifications found in earlier chapters of the HTS. While siblings in Chapter 99 might also represent temporary restrictions or special provisions, the specific conditions of aluminum origin and Mexican manufacturing clearly delineate the scope of 9903.85.71. It is crucial to differentiate this from other temporary measures that may not have the same origin-specific requirements for aluminum inputs.

As this is a leaf node within the HTS, there are no further subcategories to explore. Classification into 9903.85.71 is definitive based on the confluence of the article being of Mexican origin, containing primary aluminum, and that aluminum having undergone smelting or casting in one of the designated countries: China, Russia, Belarus, or Iran. Importers must carefully trace the supply chain of their aluminum inputs to ensure accurate classification under this provision.