US doesn't dictate to Aust on navy: Bishop

Foreign Minister Julie Bishop has indicated Australia could resist US calls for the navy to conduct joint freedom of navigation patrols in the South China Sea, despite US President Donald Trump saying he would "love" it to happen.

Ms Bishop says Australia already upholds its rights to freedom of navigation and overflight of the South China Sea.

"If we decide that we need to undertake more exercises in the South China Sea then we'll do it. But it's not for other countries to dictate to Australia and they don't," she told ABC radio on Tuesday.

Meanwhile, former prime minister Kevin Rudd has angrily hit out at "defamatory accusations" that he is somehow a complicit agent of the Chinese state because he has dared to point out the Turnbull government's hypocrisy on China.

"Why has Turnbull suddenly changed from being an apologist to being a McCarthyist; what is the evidence of China's effective official subversion of the Australian state from within," Mr Rudd mused in a letter to the Canberra Times.