Entry requirements are the same as United States of America. Entries are handled the United States customs and Immigration service.
Nationals from Australia, Brunei, China(14 days), Hong Kong, Japan, Malaysia, Nauru, New Zealand, Papua New Guinea, Singapore, South Korea, Taiwan and United Kingdom can enter for up to 45 days without the need of an ESTA or a visa,
Northern Mariana Islands Entry requirements
North Mariana Islands Tourism