Marles, who is also Defence Minister, is making his first trip to the US since the Labor government won office.
In a speech to a US think-tank overnight, he said Australia would “do its share” to bolster its military capabilities in the Indo-Pacific to deter coercion in the region.
He said Australia and the US must work together to counter aggression and preserve the international rules-based order. Failure to follow this would mean a “catastrophic failure of deterrence” Marles warned.
“We can’t afford to stand still,” Marles said in a speech to the Centre for Strategic and International Studies in Washington.
“In the years ahead, the US-Australia alliance will not only have to operate in a much more challenging strategic environment in the Indo-Pacific; it will need to contribute to a more effective balance of military power aimed at avoiding a catastrophic failure of deterrence.”
He highlighted Australia’s concern about the use of force and coercion to advance territorial claims “as is occurring in the South China Sea”.
The vast South China Sea has become hotly disputed between China and other countries, including Australia.
Tensions in the contested waters have ratcheted up since 2014 as China has turned sandbars into islands, equipping them with airfields, ports and weapons systems and warned Western warships and aircraft to stay away from them.
Marles also alluded to Russia’s invasion of Ukraine when he warned of the dangers from one nation’s military expansion.
“Events in Europe underline the risks we face when one country’s determined military build-up convinced its leader that the potential benefit of conflict was worth the risk.”
Marles said the Australia was committed to taking greater responsibility for the nation’s security.
“We will make the investment necessary to increase the range and lethality of the Australian Defence Force so that it is able to hold potential adversary forces and infrastructure at risk further from Australia.”
During his US visit, Marles will hold talks with Defence Secretary Lloyd Austin to discuss military ties including the AUKUS agreement under which Australia will acquire nuclear-powered submarines.
It comes one month after Marles met his Chinese counterpart in Singapore in which he said the pair had a “full and frank discussion”.
And last week Foreign Minister Penny Wong met with China’s Foreign Minister Yi Wang for the first time since 2019.
Days later Chinese officials released a to-do list of four demands it wants Australia to meet if relations were to grow closer.
This week Prime Minister Anthony Albanese and Wong are attending the Pacific Islands Forum meeting in Fiji where China and climate change are expected to dominate the agenda.