Whoever imports "the importer" is to follow FSVP. So in this case the US ingredient supplier who is importing into USA is the one responsible.
Who Is Covered by the FSVP Rule?
The FSVP importer is the U.S. owner or consignee of the food offered for import (i.e., owns the food, has purchased it, or has agreed in writing to purchase it at the time of U.S. entry). If there is no U.S. owner or consignee at time of entry, the FSVP importer is the U.S. agent/representative of the foreign owner/consignee, as confirmed in a signed statement of consent. The key is that there be a FSVP importer in the United States who takes responsibility for meeting the FSVP requirements.