although tensions between the government and tamil militant groups had been brewing since the 1970s , full-scale war did not break out Process_start until an attack Attack by the ltte on a sri lanka army patrol in jaffna , in the north of the country , on july 23 , 1983 , which killed Killing 13 soldiers .

this was used Using to take down two sri lankan air force avro aircraft flying Motion over the jaffna peninsula .