He is a graduate of the Defence Services Staff College in India and the Royal College of Defence Studies, UK. He holds a Ph.D. from General Sir John Kotelawala Defence University (Sri Lanka). His doctoral thesis; ‘Asymmetric Warfare at sea: The Case of Sri Lanka’ is now published. He also holds MSc in Defence and Strategic Studies from Madras University and MA in International Studies from Kings College, London.
He is a visiting lecturer at the University of Colombo, Defence Services Command and Staff College (Sri Lanka), Kotelawala Defence University, and Bandaranaike International Diplomatic Training Institute. He is a Fellow of the Nautical Institute, London UK. Admiral Colombage is a Guest Professor at Sichuan University and Leshan Normal University in China and an adjunct professor at the National Institute of South China Sea Studies, Haikou, China. In addition. He has been a guest lecturer in several key universities and research institutes in Bangladesh, India, Japan, and Pakistan. He has also been an editor and reviewer of a number of internationally renowned academic journals. In addition, he has served as the Director General of the Institute of National Security Studies Sri Lanka as well. He is currently a Ph.D. examiner for the University of Colombo.
Admiral Colombage held the portfolio of Additional Secretary to H.E. the President for Foreign Relations. Admiral Colombage was also the Secretary to the Foreign Ministry from August 2020 to May 2022.
Currently, Admiral Colombage is serving as the Ambassador of Sri Lanka to Indonesia since 2023.