The International Institute for Strategic Studies (IISS) is an international research institute or think tank focusing on defence and security issues. Since 1997, its headquarters have been at Arundel House in London. It has offices on four continents, producing data and research on questions of defence, security and global affairs, publishing publications and online analysis, and convening major security summits. The Guardian newspaper has described the IISS as ‘one of the world’s leading security think tanks.’

Arundel House was a London town-house located between the Strand and the River Thames, near the Church of St Clement Danes.