33 CFR §151.29

1. (a)Each oil tanker of 150 gross tons and above and each other ship of 400 gross tons and above, operated under the authority of a country other than the United States that is party to MARPOL 73/78, shall, while in the navigable waters of the United States or while at a port or terminal under the jurisdiction of the United States, carry on board a shipboard oil pollution emergency plan approved by its flag state.
2. (b)Each oil tanker of 150 gross tons and above and each other ship of 400 gross tons and above, operated under the authority of a country that is not a party to MARPOL 73/78, must comply with § 151.21 of this subpart while in the navigable waters of the United States.