Mr. Biden’s remarks presented an immediate and probably unwanted challenge for Australia’s new prime minister, Anthony Albanese. Just hours after he was sworn in on Monday, Mr. Albanese flew to Tokyo with his new foreign minister, Penny Wong, who had harshly criticized her party’s election opponents during the campaign for suggesting that Australia would follow the United States into any war over Taiwan.

“Amping up the prospect of war against a superpower is the most dangerous election tactic in Australian history,” Ms. Wong said at the time…

Now, raising questions once more about whether Australia would support a military defense of Taiwan could throw off whatever détente might be emerging. It also might shift the focus from subjects Mr. Albanese’s government would rather emphasize: greater ambition on climate change and increased aid and diplomatic engagement with countries in Southeast Asia and the Pacific islands.

Mr. Albanese and his administration would prefer “cautious, incremental change” on China, said James Curran, a historian at the University of Sydney. At the same time, he added: “They will not want to be seen easing up the pressure in terms of our policy on China.”