Rusi or RUSI may refer to:

• Ruși River, Romania
• Ruși, a district in the town of Zlatna, Alba County, Romania
• Ruși, a village in Bretea Română, Hunedoara County, Romania
• Ruși, a village in Slimnic, Sibiu County, Romania
• Ruși, a village in Forăști, Suceava County, Romania
• Ruși, a village in Puiești, Vaslui, Romania

The Royal United Services Institute for Defence and Security Studies (RUSI), officially still known by its old name, the Royal United Services Institution, is a British defence and security think tank. It was founded in 1831 by the Duke of Wellington, Sir Arthur Wellesley. RUSI describes itself as "the leading forum in the UK for national and international Defence and Security". It won Prospect Magazine's Think Tank of the Year Award 2008. In 2009, the same magazine named RUSI "Foreign Policy Think Tank of the Year". In 2011 RUSI celebrated its 180th Anniversary. RUSI's President is HRH the Duke of Kent and its Director is Michael Clarke.

Rusi or RUSI may refer to:

• Ruși River, Romania
• Ruși, a district in the town of Zlatna, Alba County, Romania
• Ruși, a village in Bretea Română, Hunedoara County, Romania
• Ruși, a village in Slimnic, Sibiu County, Romania
• Ruși, a village in Forăști, Suceava County, Romania
• Ruși, a village in Puiești, Vaslui, Romania

The Royal United Services Institute for Defence and Security Studies (RUSI), officially still known by its old name, the Royal United Services Institution, is a British defence and security think tank. It was founded in 1831 by the Duke of Wellington, Sir Arthur Wellesley. RUSI describes itself as "the leading forum in the UK for national and international Defence and Security". It won Prospect Magazine's Think Tank of the Year Award 2008. In 2009, the same magazine named RUSI "Foreign Policy Think Tank of the Year". In 2011 RUSI celebrated its 180th Anniversary. RUSI's President is HRH the Duke of Kent and its Director is Michael Clarke.