Australia will expand its mission in Iraq to train local paramilitary police as well as the army, Malcolm Turnbull has announced, underscoring the challenge Iraqi authorities face in stabilising territory recaptured from the Islamic State terror group. 
Mr Turnbull made the announcement after talks with US Vice-President Joe Biden in Sydney that also covered the South China Sea and last week's damning legal ruling against China.
Mr Biden emphatically and repeatedly stated that the US was "here to stay" in the Asia-Pacific region, reflecting nervousness among some countries about a possible American retreat in the face of China's rise.
It is understood the police training will be carried out by the 300 existing Australian Defence Force soldiers who are currently training local forces at Camp Taji, just north of Baghdad. It is unusual for police training to be done by the ADF, though Mr Turnbull said it would apply to gendarmerie forces, which are paramilitary in their function.
"We will expand the training mandate of our building partner capacity mission in Iraq to include the training of Iraqi federal law enforcement agencies and local police," Mr Turnbull said.
"At the moment our training mandate is restricted to training the Iraqi army ... one of the most important objectives now in Iraq is to ensure that the Iraqi police forces, their gendarmerie forces, are able to maintain the peace in areas that have been liberated from Daesh or ISIL as the Iraqi security forces and counter-terrorism forces progress."
Normally the training of overseas police forces has been carried out by the Australian Federal Police's International Deployment group, who have trained counterparts in countries such as Afghanistan, the Solomon Islands and East Timor.
Neil James, executive director of the Australia Defence Association, said keeping peace after areas had been liberated would fall in between the ADF's and the AFP's expertise. "Presumably this is a transition thing," he said. "If it's a post-liberation stabilisation mission ... it obviously falls into the middle ground and no doubt both the AFP and ADF will co-operate in working out what training is required."
Peter Jennings, executive director of the Australian Strategic Policy Institute, said soldiers and police had different functions but the government was likely to be reluctant to deploy AFP to such a high-risk theatre.
Fairfax Media understands the 300 existing troops will be joined by an additional 15 ADF to train the Iraqis in counter-measures against rocket, artillery and mortar fire.
And the trainers will be able to work out of other secure bases as required - a change in the current arrangement that keeps them at Taji.
Mr Biden said Australia and the US had long "had each other's back". "And I assure you, the United States is going nowhere," he said. "The United States is here in the Pacific to stay. We are a Pacific nation. We are a Pacific power. And we will do our part to maintain peace and stability in the region."
Both leaders repeatedly spoke of the importance of a rules-based or international "order" in clear signals to China over its vow to ignore the recent international tribunal ruling against its assertive behaviour in the South China Sea.