In China, history tends to get politicized. Visitors to a Tang-dynasty museum outside Xian, for example, are treated to a carefully controlled message. The Tang era (A.D. 618 to 907) is described as China's golden age, a heyday of elegance and commerce. A plaque in the exhibit states the theme bluntly: "The prosperity of Tang had [a] direct connection with its all-round open policy ... From here, the advanced culture of Tang spread out, and the gems of the outside civilization came in."

The moral is unmistakable: China prospers when it reaches out to the world. The idea is dear to the country's current leaders, who have staked their reputations on furthering China's economic rise and smoothing out its rough edges. To that end, Beijing has been vigorously courting countries throughout Southeast Asia, the Middle East, Africa and Latin America, promoting a "harmonious world" abroad while it pushes for a more equitable "harmonious society" at home.

Sounds good, but there's a catch. Being a prosperous and successful great power today requires more than just trade, tribute and mutual back-scratching among sovereigns. From Darfur to Burma, various crises are forcing China to recognize that being a serious international player means accepting some responsibility for maintaining international order.

Recent signs seem promising. China has begun taking baby steps away from its longstanding position on nonintervention abroad. It's helped push the North Korean government into a nuclear-disarmament deal and reversed its opposition to U.N. intervention in Darfur. It's even exerted modest pressure on Sudan to accept U.N. troops and committed 400 of its soldiers—medical officers and engineers—to the mission. Consistent with this new role, some academics now suggest that when the Communist Party's 17th congress opens on Oct. 15, officials will not only reaffirm their commitment to a harmonious region but also make clear that China is prepared to join in peacekeeping missions in Asia.

More U.N. peacekeepers—or peacemakers—are urgently needed in Afghanistan, which China has resolutely avoided till now. And there's a crisis looming even closer to home: in Burma, where antigovernment demonstrations have been met with violent reprisals. The crackdown demands an international response. Two years ago, the U.N. General Assembly adopted a doctrine known as the "responsibility to protect," under which all U.N. members affirmed their duty to protect their own people from genocide, war crimes, ethnic cleansing and crimes against humanity. The General Assembly also committed the United Nations to take collective action should a member state "manifestly fail" to live up to this obligation. With the Burmese generals now turning on their own people—at the same time as world leaders are declaring their commitment to peace and human rights at the U.N. in New York—the Security Council must act.

That will put China, Burma's closest friend and a permanent member of the Security Council, in a tough spot. Although Beijing blocked two Council resolutions condemning Burma this year, in September China's former foreign minister reportedly urged his Burmese equivalent to restore stability, promote reconciliation and "move toward a democracy process that is appropriate for [Burma]." Until Darfur, Beijing generally argued against interventions in other states and hoped in turn to be left alone. But as a rising great power determined once again to export its civilization throughout the world, China no longer has the luxury of staying out.