The political gulf between the major parties on whether to launch naval and air challenges to China over its artificial islands has deepened dramatically with Malcolm Turnbull slamming Labor's more hawkish stance as showing "immaturity and unreadiness" to take responsibility for national security.

Labor defence spokesman Richard Marles made it clear on Tuesday that it would always be a government decision whether or not such a challenge were launched by Australian military ships and planes, though operational details would be a matter for the Australian Defence Force.

Mr Marles told Fairfax media last week that the Navy and Air Force should be "fully authorised" to carry out high-stakes "freedom-of-navigation operations" in which a ship or plane is sent within 12 nautical miles of one of China's man-made islands in the South China Sea to demonstrate that Australia regards those waters as international.

Former prime minister Paul Keating launched a broadside at Mr Marles' position on Tuesday, telling The Australian that the shadow defence minister was wrong if he was suggesting the decision to carry out the patrols should be an operational one left to the military, rather than a political decision by the government.