<br/>Prime Minister Dr Manmohan Singh left for Washington this morning to attend the Nuclear Security Summit being hosted by US President Obama on Monday and Tuesday. <br/><br/>This summit aims to enhance international co-operation to prevent nuclear terrorism and issue which is the most immediate threat to global security. <br/><br/>In his departure statement ahead of his visit to United States and Brazil, the Prime Minister welcomed President Obama’s initiative to hold a summit on nuclear security. <br/><br/>Dr. Singh expects the summit to focus on nuclear terrorism and proliferation of sensitive nuclear materials and technologies. Dr. Singh said that India has been a consistent advocate of complete and universal global nuclear disarmament and is among the first countries in the world to call for a world-free of nuclear weapons.<br/> <br/>AIR correspondent Sarita Brara reports from Washington that final touches were given to the summit documents where India was represented by Foreign Secretary Nirupama Rao. <br/> <br/>From Washington, Dr. Singh will proceed to Brasilia to attend the 4th IBSA Summit and the 2nd BRIC Summit. <br/><br/>These grouping reflect the growing role of emerging economies in shaping the global economic order. <br/>