We will likely look back on 2015 as a consequential year in China’s evolving global strategy. The September crash of the stock market in Shanghai marks the first contemporary occasion when China’s internal difficulties have had global consequences. In November, China will take over the leadership of the G-20 and have an opportunity to put its stamp on the evolving tools of global governance. And on September 28, President Xi Jinping will address the world during the 70th anniversary of the only global body in which China already has full powers—the United Nations.

A rising power, cut from different cloth

But with greater consequence comes greater responsibility. President Xi’s job at the U.N. in 2015 will be harder than in recent years. For the past several years the international community has been transfixed by the narrative of the rising powers, and of American, or at least Western, decline. Now, America’s economic recovery, its energy revolution, its leadership on Ebola, and its re-engagement around the Islamic State (or ISIS)—however partial—has gutted the “American decline” narrative.

And Xi’s putative allies in the forging of a post-American order—Russia, Brazil, and India—won’t be nearly the help to China they have often been presumed to be. President Vladimir Putin will speak against the backdrop of Russia’s aggressive strategy in Ukraine and now Syria; Brazil’s President Dilma Roussef against the backdrop of a deep recession and a huge corruption scandal; and while President Narendra Modi is still riding relatively high internationally, he’s hardly riding in a pro-China direction.

China is more consequential than any of these other three, of course. But it faces its own challenge to its narrative as it doubles down on its assertive posture in the South China Sea and as its handling of the stock market collapse shows serious cracks in the narrative of the “Beijing model.” As Chinese growth has slowed, especially in the manufacturing sector, so has its consumption of global commodities—and the knock-on effect has been slower growth in dozens of developing countries that had ridden China’s boom. China isn’t quite the alternative “pole” to the West it has been hyped to be.

Still, China is now clearly the number two economy in the world; the number two defense spender; the dominant force in politics and economic integration in East Asia; and an increasingly important voice on global issues. So hype and narrative aside, the world will be listening closely to what President Xi has to say at the U.N.—as they will when he takes the reigns of the G-20.

In what direction is Chinese leadership heading?

At a 700-person-strong gala dinner in Seattle on Tuesday, President Xi rehearsed the arguments. China is committed to a peaceful rise. China has learned the lesson of the Second World War, and recognizes that military hegemony is not an option. China is committed to the multilateral order, and the U.N. Charter. He even teased the international relations scholarly community: “There is no Thucydides trap,” he said, referring to the idea that the growth of Chinese power will cause fear in the United States and lead to war. He stressed his theme about forging a “new kind of great power relations” that eschewed military competition for more creative approaches to cooperation on win/win issues.

All these would be welcome messages at the U.N., and if he means it, they are profoundly important messages. But if Xi wants these messages to be believed, if he wants to gain credibility at the global level, he’s going to have to do more than just talk a good game.

First, China is going to have to start acknowledging that leadership is less about abusing the privileges of power and more about absorbing costs. The world may be hungry for leadership, but it’s not hungry for leadership of the abusive kind. It’s hungry for actors capable and willing to set a direction and bear the lion’s share of the costs of action—because that’s the only thing that’s ever overcome the collective action challenges that otherwise bedevil cooperation at the international level.

Second, he has to put his strategy where his principles are. He could start with the U.N. Charter. It’s an essential document of the international order, but only if the great powers abide by its essential principles (not by every detail.) The most essential of these are the prohibition against the acquisition of territory by force and the assertion of non-interference in sovereign affairs (except with the backing of the Security Council). The United States has violated these principles, notably in Iraq—its violation was of a temporary nature, of course, but had huge consequences. Russia has violated these principles—its violation in Crimea is modest in scale but notionally permanent and a fundamental violation of the foundational principles of the U.N.

China’s actions in the South China Sea have been more subtle than these, but no less invidious or injurious to the notion of a stable international order. If China wants others to believe that it still intends for its rise to be peaceful, it needs urgently to shift strategy in the South China Sea—and it would be in a strong position, then, to call on the other great powers to recommit themselves to the principle of the non-use of force and respect for sovereignty.

I’m reasonably optimistic about the first idea. China was among the most neuralgic of countries when it came to the global response to SARS a decade ago; it’s learned its lesson and was far more forward leaning on Ebola. It chipped in, albeit not to scale, on the eurocrisis. It’s made financial contributions to the counter-ISIS campaign. And it’s made commitments that, if kept, will make a vital difference on the climate. These efforts represent a serious start, and if President Xi expands China’s role in this kind of leadership it could position him well on global issues—especially during his G-20 presidency.

I’m not so optimistic about the second. China shows every sign of being locked in an assertive-tilting-to-aggressive strategy in the South China Sea, consequences be damned. And with Russia also seemingly locked into a “wrong-foot the West” strategy, the United States and its allies will increasingly be pulled into an escalatory response—creating exactly the kind of Thucydidean trap President Xi ostensibly wants to avoid. (The United States bears responsibility here too, and it can also take steps to lower tensions in Asia.)

The problem is, the further out we go along the pathway of security tensions in Asia, the more we undermine the prospects for win-win cooperation on global challenges like terrorism and climate. For now, these twin strands of strategy are in roughly equal balance—both rivalry and restraint are leitmotifs of Xi’s worldview, and of America’s. But 2015 is going to be an important testing time for the viability of this dual-strand approach. If Xi wants to start tilting the balance to win/win approaches, his speech at the U.N. is a good place to start. But even that would only be a beginning.