There has been much talk about America’s decline in recent years, with the corollary that China will take its place. But, while the United States does indeed face problems that urgently need to be addressed, if China is to rise further, to say nothing of supplanting the US internationally, it must first put its own house in order.Those who argue that America is in decline have a difficult case to make in economic terms. For all its recent woes (which many countries would gladly exchange for their own), the US remains a dynamo of industry and innovation, and may be emerging as an energy powerhouse as well.What threatens America’s global leadership is, rather, some of the most divided and disruptive domestic politics in its history. A country whose people have traditionally prided themselves on practicality is experiencing a debilitating bout of excessive theorizing, ideology, and so-called "new ideas,” thereby forestalling the practical ideas that come from constructive interaction with one’s political opponents.The demise of compromise and collegiality in domestic politics has raised new challenges in America’s interaction with others as well. Foreign-policy debate in the US has become a proxy for who is "tougher,” which does not necessarily mean wiser.Thus, the American art of diplomatic engagement, the ability to talk with different sides while holding one’s own views to oneself, has been largely replaced by a penchant for loud talk, finger-pointing, self-righteousness, and recrimination. Countries used to welcome and look for American engagement. Now some are more likely to fear it, especially if it comes in the form of playing to domestic American constituencies’ appetite for supposed toughness.But, before the US hands over international leadership to the Chinese, it would be instructive to look at China’s own internal political divisions and inability to synchronize its domestic politics with its growing global responsibilities. China’s problems make those afflicting the US polity seem trivial in comparison.In recent years, China has been increasingly embroiled in a nineteenth-century-style dispute with several of its Southeast Asian neighbors over conflicting claims to the South China Sea. Before one laments Americans’ unwillingness to crack a history book on an international subject, it is enlightening to watch China in action, systematically complicating its vitally important relationships in the region over…what?China’s so-called "nine dashes” claim, which essentially seeks to turn the entire South China Sea into a southern Chinese lake, represents a legacy of Chiang Kai-Shek’s Republic of China. And where did the Generalissimo find the inspiration for this claim? China argues that the waters have been Chinese for a thousand years, but the likelier inspiration is more recent, reflecting Imperial Japan’s occupation of Taiwan until 1945. Thus, China, whose culture and achievements are the envy of the world, is today in a war of words – and a few naval vessels as well – with almost all of its southern neighbors over a recently inherited claim on an issue that calls for a respectful process of international negotiation.Various considerations typically underlie policy choices in such situations. But, in the case of China’s ham-handedness in the South China Sea, domestic constituencies decrying "weakness” and demanding toughness from political leaders are a key factor. Among China’s 500 million Internet users, for example, one senses a palpable rise in nationalist sentiment, reflected in bitter criticism of official "weakness” in defending Chinese interests.China’s government is extremely sensitive to such attacks. If a Chinese blogger criticizes the government over its crackdown on Falun Gong, or supports Tibet’s opposition, the Internet police rush to the scene of the supposed crime. But if the blogosphere emits jingoistic calls for more raw materials, the government salutes and works harder to obtain them.Domestic pressures have tied China in knots on other issues as well. Many international observers might forgive China its behavior in the South China Sea, given that many countries, large and small, have maritime disputes with neighbors. But China’s own constituencies, whether netizens or competing official institutions, have contributed to an international record that is earning China derision from small neighbors and great powers alike.China’s continued support for a nuclear aspirant like North Korea is a case in point. No responsible country in the world today sees any merit to North Korea’s behavior. Yet China’s preoccupation with its internal politics is such that it cannot see the price that it pays for reacting to every North Korean outrage with only vague opprobrium, combined with expressions of hope-over-experience that North Korea will reform. For example, the equanimity of its response to North Korea’s military attacks against South Korea in 2010 left South Koreans, who are also China’s neighbors, in despair about bilateral relations.The origin of China’s desultory policy lies in its leadership’s failure to shape or sharpen the drift of domestic politics: many Chinese still see plucky little North Korea as a friend and ally. So China does nothing to signal a more serious way forward, much less earn respect in the broader international community, which is now thoroughly disgusted by North Korea’s behavior.The list of untenable policies goes on. Syria is the latest international problem that China, again constrained by domestic politics, cannot seem to get right. No one expects China to line up in perfect formation with the US or the European Union on this and other issues. But its consistent preference for lining up on the other side of the divide – even when doing so runs counter to its own national interests – calls into question whether it has the internal fortitude to be a leader.None of this is meant to minimize the consequences of political polarization in the US. But, whereas America’s problem in the world today is that domestic pressures sometimes lead to an excess of fortitude, China’s problem is that similarly constraining pressures produce foreign-policy weakness.Christopher R. Hill, currently Dean of the Korbel School of International Studies at the University of Denver, was one of the main architects of American diplomacy in the 1990’s and 2000’s.Copyright Project-Syndicate.org