As the last Australian troops leave Afghanistan's Oruzgan Province, the prime minister assured families of dead and wounded soldiers that the nation's longest-ever deployment was worth the sacrifice.
Forty Australian military personnel died and 261 were seriously injured during a decade of conflict in the war-torn country.
The last of Australia's troops left Oruzgan Province on Sunday.
Mr Abbott described their departure as "bittersweet", acknowledging the deployment of 26,000 personnel over the years had come at a cost.
"I accept that we have as a nation paid a high price," he told reporters in Sydney on Monday.
"I accept that 40 families have paid an almost unbearable price.
"Nevertheless, if you look at the benefits for our country, for Afghanistan, and for the wider world, my conclusion is yes, it has been worth it."
Australian special forces soldiers were first sent to Afghanistan in late 2001 and into Oruzgan Province in late 2005.
Numbers eventually peaked at more than 1500.
In moves to pass security responsibility to Afghan forces, Australia planned to hand over the base at Tarin Kowt and withdraw from Oruzgan by the end of this year.
About 400 military personnel will stay in the country for next year, mainly in Kabul and Kandahar, in training and advisory roles.
The Australian government has also committed to spending about $100 million a year on the Afghan national forces, Mr Abbott said.
He played down speculation Taliban fighters would seize on the withdrawal of Australian troops.
"We have no crystal ball," he said.
"But it's very easy to be defeatist at a time like this, and I don't think there's all that much evidence to justify it."
Defence Minister David Johnston said he was confident local military officers were up to the job.
"This last fighting season, the Afghan national army has virtually fought without supervision," Senator Johnston said.
Also on their way to Australia are Afghan language interpreters who worked with Australian forces, and whose employment placed them at considerable risk of retaliation.
