Malcolm Turnbull has warned Asia's defence ministers of the dangers of Chinese aggression.

Key points: Malcolm Turnbull is in Singapore and gave an address to the Shangri-La dialogue

Malcolm Turnbull is in Singapore and gave an address to the Shangri-La dialogue He said China would "best succeed by respecting the sovereignty of others"

He said China would "best succeed by respecting the sovereignty of others" Mr Turnbull and his wife Lucy visited the Kranji War Cemetery — where more than 1,000 Australians are buried

Mr Turnbull gave a blunt keynote address to the Shangri-La dialogue in Singapore, implying that China was not playing by the rules in the South China Sea.

"We should be under no illusions," he told delegates.

"If we are to maintain the dynamism of the region then we must preserve the rules-based structure that has enabled it thus far.

"This means cooperation not unilateral actions to seize or create territory or militarise disputed areas."

A tribunal in the Hague has already said China has no right to claim disputed islands and shoals as its own, and should not be building on them.

Mr Turnbull dug deep into the history books to explain why an aggressive China was bad for the globe.

Beware of the Thucydides trap, he warned, referring to conflict that began because ancient Athens frightened its neighbours.

He told the audience why it was in China's interests to get on with countries like the Philippines and Vietnam.

"Just as modern China was founded in 1949 on an assertion of national sovereignty, so will 21st century China best succeed by respecting the sovereignty of others and in so doing build a reservoir of trust and cooperation with its neighbours," he said.

"And it has no better or more urgent opportunity to build that trust than to use its great leverage, and honour the responsibility with which it comes, to curb the unlawful, reckless and dangerous conduct of North Korea, including by enforcing sanctions."

US Defence Secretary Jim Mattis praised Mr Turnbull's comments in his own speech, in which he said Washington would not accept China's militarisation of the South China Sea.

Responding to questions from reporters, Mr Turnbull denied Australia was acting as "deputy sheriff to the US" and reiterated his earlier comments.

"I talked about the vital importance of maintaining the rule of law in our region and how important it was that the big fish, the little fish and the shrimps can live together under the rule of law without coercion, without being bullied or pressured by other parties," he said.



Before his address on the dangers to peace in the region, Mr Turnbull and wife Lucy visited a reminder of Singapore's own bloody history — Kranji War Cemetery — where more than 1,000 Australians are buried.

And as the battle between Philippines' troops and Islamic extremists rages on the island of Mindanao, Mr Turnbull spoke of what could happen when extremism went unchecked.

"With the bitter memory of the 2002 Bali bombing, I am keenly alert to the risk that the next mass casualty attack on Australian victims could well be somewhere in South-East Asia, where ISIL propaganda has galvanised existing networks of extremists and attracted new recruits," he said.

"As ISIL's so-called caliphate is destroyed in Syria and Iraq more fighters will seek to return to the region — battle hardened and trained.

"Just as the terrorists networks are transnational so must be our collaboration — and nowhere more so in the sharing of intelligence.

"Australia will continue to assist our friends in the region and beyond."