The signing of a 10-year defence pact between India and the US is the first formal upgrade to bilateral military ties since New Delhi tested nuclear weapons in 1998 and marks a new high in relations between the world's largest democracy and the most powerful one.

Donald Rumsfeld, US defence secretary, declared the start of a “new era” in bilateral relations, a sentiment echoed by co-signatory Pranab Mukherjee, India's defence minister and de facto deputy-prime minister.