Formará parte de del archipiélago de Puerto Rico, pero:
Desecheo is a small uninhabited island of the archipelago of Puerto Rico located in the northeast of the Mona Passage; 21 km from the west coast (Punta Higüero) of the main island of Puerto Rico and 50 km northeast of Mona Island. It has a land area of 1.5 km² (exactly 1,524,613 m², or 0.589 sq mi, or 376.74 acres). Politically, the island is administered by the U.S. Department of the Interior, U.S. Fish and Wildlife Service. It was discovered by Christopher Columbus during his second voyage to the New World, however it was not named until 1517 by Spanish explorer Nuñez Alvarez de Aragón.
Ahí no pasa nadie sin permiso americano. Por cierto, Purto Rico es independiente, pero con muchos matices, o sea que imagínate para esa Isla
Para más info:
http://en.wikipedia.org/wiki/Puerto_Rico