19 CFR 122.32 - Aircraft required to land.
(a) Any aircraft coming into the U.S., from an area outside of the U.S., is required to land, unless it is denied permission to land in the U.S. by CBP pursuant to § 122.12(c), or is exempted from landing by the Federal Aviation Administration.
(b) Conditional permission to land. CBP has the authority to limit the locations where aircraft entering the U.S. from a foreign area may land. As such, aircraft must land at the airport designated in their APIS transmission unless instructed otherwise by CBP or changes to the airport designation are required for aircraft and/or airspace safety as directed by the Federal Aviation Administration (FAA) flight services.