Quoting one of the lawyers who helped draft sanctions law:
https://freekorea.us/sanctions-nkspea-faq/
""" Section 207 of the NKSPEA contains broad exemptions for food imports and humanitarian aid, and provides for waivers for humanitarian reasons, or when a waiver is important to the national security or economic interests of the United States. The Treasury Department has also published general licenses permitting humanitarian aid. """