The British Indian Ocean Territory Police serve in the British Indian Ocean Territory (BIOT).
It consists of Royal Overseas Police Officers (ROPO), that are all currently members of either the Royal Marines or Royal Navy.
These officers also act as customs officers for the island of Diego Garcia in the British Indian Ocean Territory.
Entry to the United States Navy East Point Plantation needs a police permit.
References
British Indian Ocean Territory Police Wikipedia(Text) CC BY-SA