Simplify the following text for a Grade 11 native English-speaking person.
Original: The Northern Mariana Islands , officially the Commonwealth of the Northern Mariana Islands ( CNMI ) , is a commonwealth in political union with the United States , occupying a strategic region of the western Pacific Ocean .
Simplified: The Commonwealth of the Northern Mariana Islands is a group of islands in the Pacific Ocean that are a political division controlled by the United States .