O'Neill was the founding chairman of the Australian Strategic Policy Institute (2000–05). He was chair of the International Academic Advisory Committee at the United States Studies Centre, University of Sydney (2008–11). He was chairman of trustees of the Imperial War Museum, London, 1998–2001 (Trustee 1990–98). He was chairman of the Council of the International Institute for Strategic Studies, 1996–2001 (council member 1977–82, 1992–96).[3]
— (1966). The German Army and the Nazi Party, 1933–1939. London: Cassell.
— (1968). Vietnam Task: The 5th Battalion, the Royal Australian Regiment, 1966/67. Melbourne: Cassell Australia.
— (1968). Indo China Tragedy, 1945–1954. Melbourne: Cheshire.
— (1969). General Giap: Politician and Strategist. North Melbourne: Cassell Australia. ISBN9780304933754.
— (1969). The Strategy of General Giap Since 1964. Canberra: Australian National University Press. ISBN978-0708105351.
— (1971). Peking-Hanoi Relations in 1970. Canberra: Australian National University Press. ISBN978-0708105375.
— (1972). The Army in Papua-New Guinea: Current Role and Implications for Independence. Canberra: Australian National University Press. ISBN978-0708105368.
—; McLean, Robyn (1972). Australia's Defence Capacity: A Compendium of Data. Canberra: Strategic and Defence Studies Centre.
—; Tie, Jolika; Langtry, John (1978). Australia's Defence Resources: A Compendium of Data. Canberra: Strategic and Defence Studies Centre. ISBN978-0908160006.
—; Fielding, Jean (1978). A Select Bibliography of Australian Military History, 1891–1939. Canberra: Australian National University. ISBN978-0908160037.
— (1985). Combat Operations. Australia in the Korean War 1950–53. Vol. 2. Canberra: Australian War Memorial and the Australian Government Publishing Service. ISBN978-0642043306.
— (1985). Australia, Britain, and International Security: Retrospect and Prospect. London: Institute of Commonwealth Studies, University of London. ISBN978-0902499416.
— (1988). Alliances and International Order: An Inaugural Lecture Delivered before the University of Oxford on 20 November 1987. Oxford: Oxford University Press. ISBN978-0199515561.
— (1992). Security Challenges for Southeast Asia after the Cold War. Singapore: Institute of Southeast Asian Studies. ISBN978-9813016439.
— (2001). Australian-British Relations: The Strategic Connection. London: Menzies Centre for Australian Studies, University of London. ISBN978-1855071179.
Editor
The strategic nuclear balance: an Australian perspective, edited by O'Neill (1975)