[1] On 1 December 1972 he was appointed Commander, Task Force Anti Illicit Immigration (TAFII) in Jaffna serving till 1 March 1976, having been promoted to the rank of colonel on 1 January 1974.

He attended the National Defence College, India and on his return he served as Competent Authority for Sri Lanka Airports.

From 13 July 1979 to 31 December 1979, Brigadier Weeratunga lead extensive operations to route out the elements of Tamil militant groups forcing them to take refuge in India and reducing their terrorist activity.

[2] He was promoted to the rank of major general and made Commander of the Sri Lankan Army on 14 October 1981, and held the post till 2 November 1985.

His tenure marked the start of the Sri Lankan Civil War with the LTTE ambush of the army patrol Four Four Bravo in July 1983.

[1] After retiring the army he was appointed as Sri Lankan High Commissioner to Canada in October 1989 and served till 1990.