The United States objected to the provisions of Part XI of the Convention on several grounds, arguing that the treaty was unfavorable to American economic and security interests. Due to Part XI, the United States refused to ratify the UNCLOS, although it expressed agreement with the remaining provisions of the Convention.
From 1983 to 1990, the United States accepted all but Part XI as customary international law, while attempting to establish an alternative regime for exploitation of the minerals of the deep seabed.