Scott Morrison has called on fellow global leaders to confront the twin threats of trade wars and violent extremism on his first visit to the United Kingdom as prime minister.
Mr Morrison arrived on Tuesday in the country, which has been politically paralysed in Brexit debate for three years, with a stern warning about a threatened global liberal order.
He pointed out tensions over Brexit, and between the US and China as indicating an urgent need to move away from a "zero-sum mindset" that heralds a lurch into a narrow, purely economic form of international relations.
The prime minister, who will commemorate the 75th anniversary of D-Day with several world leaders on Wednesday, sees the current international system as the embodiment of the shared experiences and values of the Allies in WWII.
He has called for immediate action to reform the World Trade Organisation so it works as a proper dispute settlement system to ensure the prosperity that underpins the global system.
"The WTO remains the best foundation we have for securing continued prosperity in a fast-changing world; as the Brexit debate in this country demonstrates only too well," Mr Morrison told the Australia-UK Chamber of Commerce in London on Tuesday.
"So we must remain committed to this task - to allow commercial society to flourish - to allow the people in this room - the entrepreneurs, the employers, the risk takers - to make the investment decisions so vital to future prosperity.
"It is critical, therefore, that like-minded countries, including Australia and the United Kingdom, lend their support to WTO reform - to mend, not end, the rules-based trading system."
The prime minister also warned about the threat of violent terrorism to the liberal world order and called on the G20 nations to join Australia in clamping down on extremist internet content.
He said counties can pass laws but social media providers must be held to account as well.
"The global community needs to make it clear to business that it is their responsibility to take down the content and, preferably, prevent it going up in the first place," Mr Morrison said.
"The platforms are not just 'posties' - they are responsible for what they deliver. There are practical reforms industry can do and standards by which the global community can hold them to account."
Mr Morrison is due to meet UK Prime Minister Theresa May, US President Trump, French President Emmanuel Macron, German Chancellor Angela Merkel, and Canadian Prime Minister Justin Trudeau at D-Day commemorations in Portsmouth on Wednesday.
