Dr. Siddhartha during 2007-09 served on invitation of the Secretary General of the United Nations as a member of the Experts Group in New York of the Committee on UN Security Council Resolution 1540. Upon returning, Siddhartha served in 2009-10 with the Principal Scientific Adviser to the Government of India as Scientific Consultant (Advanced Technologies). An Emeritus Scientist in DRDO, he retired in 2004 after working directly with four Scientific Advisors to the Raksha Mantri over nearly twenty years. Dr. Siddhartha has been twice Consultant to the Ministry of External Affairs, Government of India, on export control and S&T issues in international security, and on the Indian WMD Act, 2005. Dr Siddhartha has also served with the United Nations Environment Programme in Geneva. He served for some time as Secretary of the Science Advisory Council to the Prime Minister. Dr. Siddhartha holds a PhD from the Imperial College of Science & Technology, London, and a B.Tech in mechanical engineering from IIT, Madras. He has served with different arms of the nation’s S&T system including the Indian Space Research Organisation (ISRO), the Council for Scientific and Industrial Research (CSIR), the Defence Research and Development Organisation (DRDO) as well as the Department of Science and Technolgy (DST). Dr Siddhartha is a founder-member of the Institute of Social and Economic Change, Bangalore. He is a member of the Aeronautical Society of India, and of the United Service Institution of India, as also of several technology associations and bodies. He was Research Fellow at the Science Policy Research Unit at the University of Sussex, UK. He has served on the Editorial Board of the journal Current Science of the Indian Academy of Sciences. In 2021 Dr. Siddhartha became, on invitation, a member of the Governing Council of the National Maritime Foundation, New Delhi, India.