The leaders of the Quad group -- Australia, India, Japan and the United States -- delivered a thinly veiled swipe at Beijing's behaviour Saturday at a summit in Hiroshima.
US president Joe Biden and his three partners in the group did not mention China by name but the communist superpower was clearly the target of language in a joint statement calling for "peace and stability in the Indo-Pacific maritime domain".
"We strongly oppose destabilising or unilateral actions that seek to change the status quo by force or coercion," the statement said, using diplomatic language that appeared to refer to China's economic tactics to gain leverage over poorer countries and also its military expansion in the Pacific.
"We express serious concern at the militarization of disputed features, the dangerous use of coastguard and maritime militia vessels, and efforts to disrupt other countries' offshore resource exploitation activities," the statement added, clearly referring to Chinese construction of bases on former offshore reefs and harassment of non-Chinese vessels in disputed waters.
The Quad leaders held their meeting while already gathered in Hiroshima for a Group of 7 summit.
Australian prime minister Anthony Albanese had been meant to host Biden, Japanese prime minister Fumio Kishida and Indian Prime Minister Narendra Modi in Sydney next week. However, Biden pulled out, saying he had to return to Washington from Japan on Sunday to negotiate with Republican opponents on the US debt ceiling.
Biden apologised for forcing the change in plans and has invited Albanese to make a state visit to the White House.
In their statement, they stressed the Quad's support for infrastructure improvements across the vast Asia-Pacific region, while saying, in another apparent dig at China, that they wanted to assist such investments but would "not impose unsustainable debt burdens" on recipients of assistance.
Among the projects the Quad leaders highlighted was the "urgent need to support quality undersea cable networks in the Indo-Pacific, which are key to global growth and prosperity". They announced a partnership aiming to draw on their countries' expertise in the specialist maritime cable sector.
They also said that an existing pilot programme for high-tech monitoring of illegal fishing would expand.
And they said they were "deeply concerned" by repression in Myanmar, and they condemned "North Korea's destabilising ballistic missile launches and pursuit of nuclear weapons in violation of multiple UN Security Council resolutions".