US ratification of UNCLOS would help secure the already favorable terms the US negotiated

Most importantly, from a national security perspective, UNCLOS’ terms are overwhelmingly favorable to the U.S. Were this not the case, additional arguments for accession would be irrelevant. To the contrary, the Convention codifies principals the U.S. national security community helped negotiate and continues to support. The Convention’s express terms give the U.S. military a comprehensive and eminently favorable basis for conducting maritime operations around the world.⁹⁶

UNCLOS, as a treaty with favorable terms, is superior to customary law (and the 1958 Geneva Conventions on the Law of the Sea to which the U.S. has long been a party) as means for preserving U.S. interests in global mobility. Treaty membership would help the U.S. better preserve the favorable terms it helped negotiate, both through formal access to the amendment processes described above, as well as through UNCLOS constituent bodies such as the International Tribunal of the Law of the Sea, the International Seabed Authority, and the Commission on the Limits of the Continental Shelf.