Royal United Services Institute
| Abbreviation | RUSI |
|---|---|
| Formation | 1831 |
| Founder | |
| Type | |
| Legal status | Nonprofit organization |
| Headquarters | Westminster, London, United Kingdom |
| Coordinates | 51°30′15″N 0°07′33″W / 51.5043°N 0.1259°W |
President | The Duke of Kent |
Chairman | Sir David Lidington |
Director-General | Rachel Ellehuus |
| Website | rusi.org |
The Royal United Services Institute (RUSI, Rusi) is a defence and security think tank with its headquarters in London, United Kingdom. It was founded in 1831 by the Duke of Wellington, Arthur Wellesley. The institution was registered as Royal United Service Institute for Defence and Security Studies and formerly known as the Royal United Services Institute for Defence Studies. The current chair of RUSI is Sir David Lidington and its director-general is Rachel Ellehuus.