Australia said Friday it would complete its mission in Afghanistan despite suffering its deadliest day in combat since the Vietnam War and the prospect of further deaths caused by rogue soldiers.
Defence Minister Stephen Smith said the "terrible combination" of three troops being shot dead by an Afghan colleague and two others dying in a helicopter crash within 24 hours was the worst scenario he had seen in the job.
"It doesn't do anything to my resolve to stay the course, because staying the course is absolutely the right thing to do," Smith told reporters.
"We can't stay in Afghanistan forever, we don't want to stay in Afghanistan forever, and equally it would be wrong to leave prematurely or to leave tomorrow as some people suggest."
Smith said an immediate withdrawal would "increase the risks", compared to the planned gradual transition in which Afghan forces will take control of security in Uruzgan province from the Australians by late 2013.
"We would increase the prospect of Afghanistan again returning to a breeding ground for international terrorism," he said.
Late on Wednesday, three Australian troops were shot dead at close range by an Afghan soldier inside a patrol base near Tarin Kowt in restive Uruzgan, where some 1,500 Australians are deployed.
In the second incident, two Australian special forces soldiers were killed when their helicopter crashed in Helmand province on Thursday morning.
NATO has struggled to counter the so-called "green-on-blue" attacks in which uniformed Afghans turn their weapons against their international allies. This was the third such incident to target Australian troops.
Smith said the attacks eroded trust between the troops and led to extra precautions, such as the use of a "guardian angel" in which one armed foreign soldier is tasked with watching Afghan soldiers to prevent attacks.
But he said there was no guarantee that this would be the last insider shooting.
"We can't discount the prospect... that it may happen again, either to us or to our NATO or ISAF (International Security Assistance Force) colleagues," he said.
A close ally of the United States, Australia has so far lost 38 soldiers in the decade-long Afghan conflict.