After years of standing up to China, Australia is now sounding an even louder alarm.Prime Minister Scott Morrison demanded on Monday that the Chinese government apologize for a tweet that showed a doctored photo of an Australian soldier with a knife at the neck of an Afghan child. But he also called for a reset in relations with Beijing.Australia’s quandary about how to deal with Beijing is one that echoes around the globe as China increasingly asserts its might.Caught between two superpowers: Australia’s jitters are partly about the limited options in the face of China’s vise. But they are also about an America in flux. Few countries have gained as much wealth from China’s growth as Australia, and Xi Jinping, China’s leader, has made clear that he expects silence and harmony from all who benefit from China’s prosperity.Disputes: Australia has tolerated China’s blockade of certain Australian imports; it now plans to file a lawsuit with the World Trade Organization over barley imports.What’s next: There is widespread concern that the new administration of President-elect Joe Biden will focus less on America’s Pacific partners and more on rebuilding ties in Europe. That has pushed Australia deeper into a position of pleading for help in corralling China, even as it pushes for sovereignty.