Beijing's support for Pyongyang is at growing odds with its international responsibilities.

North Korea's long-range missile test has put the hermit kingdom back on America's radar. Experts are already scrutinizing the launch for clues as to Kim Jong Un's grip on power, the state of the country's nuclear program, and even what it could mean for South Korea's looming presidential elections. But in the wake of the test, there's only one country that really matters -- and it's not the one with a 29-year-old at the helm.

It's China.

North Korea's closest ally will be more important than ever in President Obama's second-term dealings with Pyongyang. In some ways, it'll be more of the same: China has long been a member of the Six Party Talks that the West has used as a bulwark against North Korea's nuclear ambitions. China is among the DPRK's biggest trading partners, and it's where the isolated state gets much of its fuel, raw materials, and finished products, such as cars. As a result, Beijing is often thought to have a good deal of sway over Pyongyang.

If China becomes a guarantor of Asia's regional security, that puts it in a contradictory position with regard to North Korea.

But China's traditional mediating role is about to get a major stress-test. For starters, the latest crisis -- if you can call it that -- poses an early challenge for China's new leaders, who were confirmed just a month ago. From the initial diplomatic response, it's hard to tell if President Xi and Prime Minister Li are working on a new approach to North Korea, or if they're simply intent on treading water. Cryptically, a spokesperson for China's foreign ministry said yesterday that his government viewed the North's missile launch with regret.

Despite tiptoeing around the problem now, the day when China is forced to take a bolder stance on its vassal may be quietly approaching. Part of this breakthrough will be rooted in China's own development as a globally relevant political force. In recent years, China's actions have demonstrated that it's interested in being part of the solution on various global security challenges. In 2008, China sent warships to the Strait of Hormuz in a collaborative bid to curb maritime piracy. This year, in a first for Beijing, it unveiled a peace proposal aimed at ending the violence in Syria. And in another sign of its expanded interest in the Middle East, China played host to a Palestinian envoy in the midst of the physical and digital conflict in Gaza last month.

Yes, taking these moves at face value could be a mistake. China certainly does its fair share to undermine other international norms. And its motivation for becoming involved in global security obviously stems in part from a desire to create outcomes that serve its interests. But consider the big picture: In doing so, China is also assuming a certain kind of responsibility that befits a world-class power. Beijing can choose many paths. It can opt to disrupt the international system -- the constellation of rules, norms and institutions that define what world politics is today. Or, it can contribute to upholding that system. Judging from its recent actions, China appears to be choosing the latter, perhaps even coming to view itself as a net contributor to global stability.

For a country that prioritizes order above almost all else in its domestic affairs, this attitude makes some sense. It wouldn't be surprising if China applied that same philosophy to its own backyard, either. China's on pace to become Asia's most powerful player -- a role that, according to some political theorists, should eventually lead to long-term regional stability. China's military buildup may be making some neighbors nervous now -- Japan, Taiwan, and India come to mind -- but few of them have the resources to expand as quickly or to the same scale.

If China becomes a guarantor of Asia's regional security, that puts it in a contradictory position with regard to North Korea. Does Beijing uphold its longtime commitment to East Asia's most troublesome, uh, bomb-thrower -- at a cost to regional stability? Or will the international role it seems so eager to embrace pressure China into reining in its client state -- bolstering Beijing's Western credentials in the process?